"Are you asking me to be your flatmate?"

He has been awake for some time, rehearsing in his head a tone of voice and phrasing that is both casual and significant, and when he feels her stir he speaks. "Can I say something?" he says into the back of her neck, his eyes still closed, mouth gummed with sleep.

"I mean you're here most nights anyway."

Belsize Park

The radio alarm sounds as usual at 07.05. It is already bright and clear outside, but neither of them move just yet. Instead they lie with his arm around her waist, their legs tangled at the ankle, in Dexter's double bed in Belsize Park in what was once, many years ago now, a bachelor flat.

With her back to him, she smiles. "O-kay."

"I think it's crazy, you having your own flat."

"No, I want you to be."

"Go on," she says, a little wary.

She opens her eyes. "I needn't be."

She turns in the bed to face him, and sees his eyes are still closed. "Dex, are you?…"

He smiles and without opening his eyes, he takes her hand beneath the sheet and squeezes it. "Emma, will you be my flatmate?"

"What?"

"I said, I'll think about it."

"I know, I just --"

"She'll get used to it. Besides, she's only two and a half, it's not up to her, is it? Or her mother."

"And it's insane for you to rent, renting is money down the drain, in the current property market."

He opens his eyes. He had expected a yes. "What's there to think about?"

"Let me think about it."

"So, what, yes?"

"We lived together in Paris."

"I know, but that was Paris."

"And what about Jasmine?"

"Nice."

"You living here."

"Finally!" she mumbles. "Dex, it's all that I've lived for."

"You sound like my independent financial adviser. It's very romantic." She pouts her lips and kisses him, a cautious morning kiss. "This isn't just about sound financial planning, is it?"

"And might it not get a bit…?"

"Mainly, but I also think it'd be… nice."

"We more or less live together now."

"What?"

"Well let me know, won't you? Because if you're not interested, I might get someone else in."

"Just, I don't know. Living together."

"Cramped. The three of us at weekends."

"And where will you take your lovers?"

"We'll manage."

"Where will I work?"

"You can work here while I'm out."

He sighs, a little bored of the joke after a year of almost maniacal fidelity. "We'll go to hotels in the afternoon."

They lapse into silence again as the radio burbles on and Emma closes her eyes once more and tries to imagine herself unpacking cardboard boxes, finding space for her clothes, her books. In truth, she prefers the atmosphere of her current flat, a pleasant, vaguely Bohemian attic off the Hornsey Road. Belsize Park is just too neat and chi-chi, and despite her best efforts and the gradual colonisation of her books and clothes, Dexter's flat still retains an atmosphere of the bachelor years: the games console, the immense television, the ostentatious bed. "I keep expecting to open a cupboard and be buried under, I don't know… a cascade of panties or something." But he has made the offer, and she feels as if she should offer something in return.

"Maybe we should think of buying somewhere together," she says. "Somewhere bigger." Once again, they have grazed against the great unspoken subject. A long silence follows, and she wonders if he has fallen asleep again, until he says: "Okay. Let's talk about it tonight."

"Course not."

Then they kiss again, and she goes to work, and he goes to work, and so the days go by, faster than ever.

"Sylvie's dropping Jasmine off at four o'clock," he says. "I'll be back at six. You're sure you don't mind being there?"

Work. He is working again in his own business, though "business" feels a little too high-powered a word at present for this little delicatessen-café on a residential street between Highgate and Archway.

"And you'll be okay with Jasmine?"

"Fine. We'll go to the zoo or something."

And so another weekday begins, like the one before and the ones to come. They get up and get dressed, Emma drawing on the limited store of clothes she keeps jammed into her allocated cupboard. He has the first shower, she has the second, during which time he walks to the shop and buys the newspaper and milk if necessary. He reads the sports pages, she the news and then after breakfast, eaten for the most part in comfortable silence, she takes her bike from the hallway and pushes it with him towards the tube. Each day they kiss each other goodbye at approximately eight twenty-five.

So in late September, when Paris had finally, finally started to lose some of its gleam, they had travelled back on the train together. With light tans and new clothes they walked arm-in-arm along the platform and it felt like they were arriving in London for the very first time, with plans and projects, resolutions and ambitions.

The idea was hatched in Paris, during that long strange summer in which they had dismantled his life, then put it back together again. It had been Emma's idea, sitting outside a café near the Parc des Buttes Chaumont in the north-east. "You like food," she had said, "you know about wine. You could sell really good coffee by the pound, imported cheeses, all that swanky stuff that people want these days. Not pretentious or chi-chi, just this really nice little shop, with tables outside in the summer." Initially he had bridled at the word "shop", not quite able to see himself as a "shopkeeper" or, even worse, a grocer. But an "imported food specialist" had a ring to it. Better to think of it as a café/restaurant that also sold food. He would be an entrepreneur.

Their friends nodded sagely, sentimentally, as if they had known it all along. Emma was introduced once again to Dexter's father -- "Of course I remember. You called me a fascist" -- and they put forward the idea of the new business in the hope that he might want to help with the financing. When Alison had died there had been a private understanding that some money might go to Dexter at an appropriate time, and this seemed like the moment. Privately, Stephen Mayhew still expected his son to lose every penny, but that was a small price to pay to know that he would never, ever appear on television ever again. And Emma's presence helped. Dexter's father liked Emma, and for the first time in some years found himself liking his son because of her.

They had found the property together. A video rental shop, already an anomaly with its shelves of dusty VHS, had finally given up the ghost, and, with one last push from Emma, Dexter had made his move and taken the property on a twelve-month lease. Through a long wet January they ripped out the metal shelving and distributed the remaining Steven Seagal videos around local charity shops. They stripped and painted the walls a buttery white, installed dark wooden panelling, scoured other bankrupt restaurants and cafés for a decent industrial coffee machine, chill cabinets, glass-fronted refrigerators; all those failed businesses reminding him of what was at stake, how likely he was to fail.

On the first day of spring they sat in the sun on the pavement outside the partly refurbished shop and wrote down a list of possible names: corny combinations of words like magasin, vin, pain, Paris pronounced "Paree", until they settled on Belleville Café, bringing a flavour of the 19th arrondissement to just south of the A1. He formed a limited company, his second after Mayhem TV plc, with Emma as his company secretary and, in a small but significant way, his co-investor. Money was starting to come in from the first two "Julie Criscoll" books, the animated TV series had been commissioned for its second series, there was talk of merchandising: pencil cases, birthday cards, even a monthly magazine. There was no denying it, she was now what her mother would term "well off". After a certain amount of throat-clearing, Emma found herself in the strange, slightly unnerving position of being able to offer Dexter financial help. After a certain amount of foot shuffling, he accepted.

But all the time Emma was there, pushing him on, keeping him convinced that he was doing the right thing. The area was up-and-coming the estate agents said, slowly filling with young professionals who knew the value of the word "artisan" and wanted jars of duck confit, customers who didn't mind paying two pounds for an irregular loaf of bread or a lump of goat's cheese the size of a squash ball. The café would be the kind of place where people came to ostentatiously write their novels.

And now the place has become fashionable, albeit in a more sedate, domesticated way than he is used to. If he is famous now it is only locally, and only for his selection of herbal teas, but he's still a mild heartthrob to the flushed young mums-to-be who come in to eat pastries after their pram-ercise class, and in a small way he is almost, almost a success again. He unlocks the heavy padlock that holds down the metal shutters, already hot to the touch on this radiant summer's morning. He pulls them up, unlocks the door and feels, what? Content? Happyish? No, happy. Secretly, and for the first time in many years, he is proud of himself.

They opened in April, and for the first six weeks he stood by the dark wood counter, watched people walk in, look round, sniff and walk out again. But then word began to spread, things began to pick up and he found himself able to take on some staff. He began to acquire regulars, even to enjoy himself.

Of course there are long boring wet Tuesdays, when he wants to pull down the shutters and methodically drink all the red wine, but not today. It's a warm day, he is seeing his daughter tonight and will be with her for much of the next eight days while Sylvie and that bastard Callum go on another of their constant holidays. By some strange mystery Jasmine is now two and a half years old, self-possessed and beautiful like her mother, and she can come in and play shops and be fussed over by the other staff, and when he gets home tonight Emma will be there. For the first time in many years he is more or less where he wants to be. He has a partner whom he loves and desires and who is also his best friend. He has a beautiful, intelligent daughter. He does alright. Everything will be fine, just as long as nothing ever changes.

Two miles away, just off the Hornsey Road, Emma climbs the flights of stairs, unlocks the front door and feels the cool, stale air of a flat that has been unoccupied for four days. She makes tea, sits at her desk, turns on her computer, and stares at it for the best part of an hour. There's a lot to do -- scripts for the second series of "Julie Criscoll" to read and approve, five hundred words of the third volume to write, illustrations to work on. There are letters and emails from young readers, earnest and often disconcertingly personal notes that she must give some attention to, about loneliness and being bullied and this boy I really, really like.

But her mind keeps slipping back to Dexter's proposal. During the long, strange summer in Paris last year they had made certain resolutions about their future together -- if in fact they did have a future together -- and central to the scheme was that they would not live together: separate lives, separate flats, separate friends. They would endeavour to be together, and faithful of course, but not in any conventional way. No traipsing around estate agents at the weekend, no joint dinner parties, no Valentine's Day flowers, none of the paraphernalia of coupledom or domesticity. Both of them had tried it, neither had succeeded.

They have spoken about it before, in a roundabout facetious way, and he has made noises about maybe, in the future, when things are a little bit more settled. But how much more settled can things be? The subject sits there in the middle of the room and they keep walking into it. It's there every time her parents telephone, it's there every time she and Dexter make love (less frequently now than in the debauch of the flat in Paris, but still often enough). It keeps her awake at night. Sometimes it seems that she can chart her life by what she worries about at three a. m. Once it was boys, then for too long it was money, then career, then her relationship with Ian, then her infidelity. Now it is this. She is thirty-six years old, a child is what she wants, and if he doesn't want it too, then perhaps they had better…

She had imagined this arrangement to be sophisticated, modern, a new design for living. But so much effort is required to pretend that they don't want to be together that it has recently seemed inevitable that one of them will crack. She just hadn't expected it to be Dexter. One subject has remained largely unspoken, and now there seems to be no way to avoid it. She will have to take a deep breath and just say the word. Children. No, not "children", best not scare him, better use the singular. She wants a child.

What? Call it a day? It seems melodramatic and degrading to issue that kind of ultimatum, and the thought of carrying out the threat seems inconceivable, for the moment at least. But she resolves that she will raise the subject tonight. No, not tonight, not with Jasmine staying, but soon. Soon.

After a distracted morning of time-wasting, Emma goes for a lunch-time swim, ploughing up and down the lanes yet still unable to clear her head. Then with her hair still wet she cycles back to Dexter's flat and arrives to find an immense, vaguely sinister black 4x4 waiting outside the house. It's a gangsters' car, two silhouettes visible against the windscreen, one broad and short, the other tall and slim; Sylvie and Callum, both gesticu lating wildly in the middle of another argument. Even from across the road Emma can hear them, and as she wheels her bike closer she can see Callum's snarled face, and Jasmine in the back seat, eyes fixed on a picture book in an attempt to filter out the noise. Emma taps the window nearest Jasmine and sees her look up and grin, tiny white teeth in a wide mouth, straining forwards against her seatbelt to get out.

Through the car window, Emma and Callum nod. There's something of the playground about the etiquette of infidelity, separation and divorce, but allegiances have been declared, enmities sworn, and despite having known him for nearly twenty years Emma must no longer talk directly to Callum. As for the ex-wife, Sylvie and Emma have settled on a tone, self-consciously bright and grudge-free, but even so dislike shimmers between them like a heat haze.

"Sorry about that!" says Sylvie, unfolding her long legs from the car. "Just a little disagreement about how much luggage we're taking!"

"Holidays can be stressful," says Emma, meaninglessly. Jasmine is unbuckled from her car seat, and clambers up into Emma's arms, her face pressed into her neck, skinny legs wrapped around Emma's hips. Emma smiles, a little embarrassed, as if to say "what can I do?" and Sylvie smiles back, a smile so stiff and unnatural that it's surprising she doesn't have to use her fingers.

"Where's Daddy?" says Jasmine into Emma's neck.

"He's at work, he'll be back very soon."

"You've been?"

"We must go. Check-in's a nightmare these days." Sylvie tucks her long legs back into the car like some sort of folding knife. Callum stares forwards.

"No, though I worked in a Mexican restaurant once."

"Mexico. Lovely."

"Mexico."

"How is that going then?" Sylvie manages. "The café?"

"Where is it again?"

Jasmine is passed back into the car for goodbyes and be-goods and not-too-much-TV and Emma discreetly takes Jasmine's luggage inside, a candy-pink vinyl suitcase on wheels and a rucksack in the form of a panda. When she comes back Jasmine is waiting rather formally on the pavement, a pile of picture books held against her chest. She is pretty, chic, immaculate, a little mournful, every inch her mother's child, very much not Emma's.

More silence. Callum gives her a nudge by starting the engine.

"Do you want to come in?" asks Emma, knowing the answer.

"Really well, really well."

"No, we should head off."

"Well I'm sorry not to see him. Send him my love."

Sylvie actually tuts, and Callum's voice booms from the front seat. "Come on! I want to avoid the traffic!"

Emma and Sylvie smile some more.

"So. Enjoy Mexico. Enjoy your snorkelling."

"So, Min, your dad's not back until six. What do you want to do?"

"Not snorkelling, scuba-diving. Snorkelling is what children do," says Sylvie, unintentionally harsh.

Emma and Jasmine stand and wave.

"It's early. We could go to the zoo?"

Emma bridles. "I'm sorry. Scuba-diving! Don't drown!" Sylvie raises her eyebrows, her mouth forming a little 'o' and what can Emma say? I meant it, Sylvie, please don't drown, I don't want you to drown? Too late, the damage is done, the illusion of sorority shattered. Sylvie stamps a kiss on the top of Jasmine's head, slams the door and is gone.

"Don't know."

Jasmine nods vigorously. Emma holds a family pass to the zoo, and she goes inside to get ready for another afternoon spent with someone else's daughter.

In the big black car the former Mrs Mayhew sits with her arms folded, her head resting against the smoky glass, her feet tucked up beneath her on the seat while Callum swears at the traffic on the Euston Road. They rarely speak these days, just shout and hiss, and this holiday, like the others, is an attempt to patch things up.

Now, whenever she sees her ex-husband he is smiling, smiling away advertising his happiness like the member of some cult. He throws Jasmine in the air, gives her piggybacks, displays at every opportunity what a wonderful dad he has become. And this Emma person too, all Jasmine talks about is Emma-this and Emma-that and how Emma is her daughter's best, best friend. She brings home pieces of pasta glued to coloured card and when Sylvie asks what it is, she says it's Emma, then chatters on and on about how they went to the zoo together. They have a family pass, apparently. God, the insufferable smugness of the pair of them, Dex and Em, Em and Dex, him with his chintzy little corner shop -- Callum has forty-eight branches of Natural Stuff now, by the way -- and her with her push-bike and thickening waist, her studenty demeanour and wry bloody outlook. To Sylvie's mind there's also something sinister and calculating in the fact that Emma has been promoted from godmother to stepmother, as if she was always lurking there, circling, waiting to make her move. Don't drown! Cheeky cow.

The last year of her life has not been a success. Callum has revealed himself to be boorish and mean. What she took to be drive and ambition have proved to be an unwillingness to come home at nights. She suspects him of affairs. He seems to resent Sylvie's presence in his home, and Jasmine's presence too; he shouts at her for merely behaving like a child, or avoids her company altogether. He barks absurd slogans at her: "Quid pro quo, Jasmine, quid pro quo." She's two and a half, for goodness" sake. For all his ineptness and irresponsibility at least Dexter was keen, too keen sometimes. Callum on the other hand treats Jasmine like a member of staff who just isn't working out. And if her family were wary of Dexter, they actively despise Callum.

Now Callum is swearing at the traffic on the Westway. She wants to have another child sometime soon, but how? Ahead of her lies a week's scuba-diving at a luxury hotel in Mexico, and she knows already that this is not going to be enough.

Beside her, Callum swears at the traffic on the Marylebone Road and Sylvie feels intense resentment at the happiness of others, combined with misery at finding herself on the wrong team for once. Sadness too, at how ugly and ungracious and spiteful all of these thoughts are. After all, it was she who left Dexter and who broke his heart.