Especially when he is plainly unable to move, and is saying, gently, "Clark. Please. Just come over here. Please."

But I couldn't. I couldn't look at him. Nathan had packed up Will's stuff, and I had met them both in the lobby the following morning -- Nathan still groggy from his hangover -- and from the moment we had to be in each other's company again, I refused to have anything to do with him. I was furious and miserable. There was an insistent, raging voice inside my head, which demanded to be as far as possible from Will. To go home. To never see him again.

There is nothing more disconcerting to passers-by than to see a man in a wheelchair pleading with a woman who is meant to be looking after him. It's apparently not really the done thing to be angry with your disabled charge.

"You okay?" Nathan said, appearing at my shoulder.

"No," I said. "And I don't want to talk about it."

As soon as we arrived at the airport, I had marched away from them to the check-in desk.

"Hungover?"

"No."

There was a short silence.

I managed to make myself busy for the entire wait at the airport. I found a thousand small tasks to do -- busying myself with luggage labels, buying coffee, perusing newspapers, going to the loo -- all of which meant that I didn't have to look at him. I didn't have to talk to him. But every now and then Nathan would disappear and we were left alone, sitting beside each other, the short distance between us jangling with unspoken recriminations.

I couldn't speak. I nodded, and I watched Nathan's jaw stiffen briefly. He was stronger than I was, though. He was, after all, a professional. Within minutes he was back with Will, showing him something he had seen in a magazine, wondering aloud about the prospects for some football team they both knew of. Watching them, you would know nothing of the momentousness of the news I had just imparted.

"This mean what I think it does?" He was suddenly sombre.

"Clark --" he would begin.

"Don't," I would cut him off. "I don't want to talk to you."

I surprised myself with how cold I could be. I certainly surprised the air stewardesses. I saw them on the flight, muttering between themselves at the way I turned rigidly away from Will, plugging my earphones in or resolutely staring out of the window.

For once, he didn't get angry. That was almost the worst of it. He didn't get angry, and he didn't get sarcastic, and he simply grew quieter until he barely spoke. It was left to poor Nathan to bounce the conversation along, to ask questions about tea or coffee or spare packets of dry-roasted peanuts or whether anyone minded if he climbed past us to go to the loo.

It probably sounds childish now, but it was not just a matter of pride. I couldn't bear it. I couldn't bear the thought that I would lose him, that he was so stubborn, and determined not to see what was good, what could be good, that he would not change his mind. I couldn't believe that he would stick to that one date, as if it were cast in stone. A million silent arguments rattled around my head. Why is this not enough for you? Why am I not enough for you? Why could you not have confided in me? If we'd had more time, would this have been different? Every now and then I would catch myself staring down at his tanned hands, those squared-off fingers, just inches from my own, and I would remember how our fingers felt entwined -- the warmth of him, the illusion, even in stillness, of a kind of strength -- and a lump would rise in my throat until I thought I could barely breathe and I had to retreat to the WC where I would lean over the sink and sob silently under the strip lighting. There were a few occasions, when I thought about what Will still intended to do, where I actually had to fight the urge to scream; I felt overcome by a kind of madness and thought I might just sit down in the aisle and howl and howl until someone else stepped in. Until someone else made sure he couldn't do it.

The two men slept, and it came as something of a relief -- a brief respite from the tension. I stared at the television screen and, with every mile that we headed towards home, I felt my heart grow heavier, my anxiety greater. It began to occur to me then that my failure was not just my own; Will's parents were going to be devastated. They would probably blame me. Will's sister would probably sue me. And it was my failure for Will too. I had failed to persuade him. I had offered him everything I could, including myself, and nothing I had shown him had convinced him of a reason to keep living.

So although I looked childish -- although I seemed to the cabin staff (as I declined to talk to Will, to look at him, to feed him) as if I were the most heartless of women -- I knew that pretending he was not there was about the only way I could cope with these hours of enforced proximity. If I had believed Nathan capable of coping alone I would honestly have changed my flight, perhaps even disappeared until I could make sure that there was between us a whole continent, not just a few impossible inches.

"No. Thank you."

"Want a drink, Clark?" Will's voice would break into my thoughts.

"No. It's fine."

Perhaps, I found myself thinking, he had deserved someone better than me. Someone cleverer. Someone like Treena might have thought of better things to do. They might have found some rare piece of medical research or something that could have helped him. They might have changed his mind. The fact that I was going to have to live with this knowledge for the rest of my life made me feel almost dizzy.

"Is my elbow too far over your armrest?"

It was only in those last few hours, in the dark, that I allowed myself to look at him. My gaze slid slowly sideways from my glowing television screen until I gazed at him surreptitiously in the dim light of the little cabin. And as I took in his face, so tanned and handsome, so peaceful in sleep, a solitary tear rolled down my cheek. Perhaps in some way conscious of my scrutiny Will stirred, but didn't wake. And unseen by the cabin staff, by Nathan, I pulled his blanket slowly up around his neck, tucking it in carefully, to make sure, in the chill of the cabin air conditioning, that Will would not feel the cold.

"Look at you!" she was exclaiming. "Will, you look wonderful. Really wonderful."

They were waiting at the Arrivals Gate. I had somehow known they would be. I had felt the faintly sick sensation expanding inside me even as we wheeled Will through passport control, fast-tracked by some well-meaning official even as I prayed that we would be forced to wait, stuck in a queue that lasted hours, preferably days. But no, we crossed the vast expanse of linoleum, me pushing the baggage trolley, Nathan pushing Will, and as the glass doors opened, there they were, standing at the barrier, side by side in some rare semblance of unity. I saw Mrs Traynor's face briefly light up as she saw Will and I thought, absently, Of course -- he looks so well. And, to my shame, I put on my sunglasses -- not to hide my exhaustion, but so that she wouldn't immediately see from my naked expression what it was I was going to have to tell her.

Will's father had stooped, was patting his son's chair, his knee, his face wreathed in smiles. "We couldn't believe it when Nathan told us you were down on the beach every day. And swimming! What was the water like, then -- lovely and warm? It's been raining cats and dogs here. Typical August!"

Of course. Nathan would have been texting them or calling them. As if they would have let us go all that time without some kind of contact.

"It… it was a pretty amazing place," said Nathan. He had grown quiet too, but now tried to smile, to seem his normal self.

I felt frozen, my hand clutching my passport like I was about to go somewhere else. I had to remind myself to breathe.

"Well, we thought you might like a special dinner," Will's father said. "There's a jolly nice restaurant at the Intercontinental. Champagne on us. What do you think? Your mother and I thought it might be a nice treat."

"Sure," said Will. He was smiling at his mother and she was looking back at him as if she wanted to bottle it. How can you? I wanted to yell at him. How can you look at her like that when you already know what you are going to do to her?

"Come on, then. I've got the car in disabled parking. It's only a short ride from here. I was pretty sure you'd all be a bit jet-lagged. Nathan, do you want me to take any of those bags?"

I was focused on my bag, deliberately not looking at them, but even above the hubbub of the airport I could detect the brief silence my words provoked.

My voice broke into the conversation. "Actually," I said -- I was already pulling my luggage from the trolley -- "I think I'm going to head off. Thank you, anyway."

Mr Traynor's voice was the first to break it. "Come on, Louisa. Let's have a little celebration. We want to hear all about your adventures. I want to know all about the island. And I promise you don't have to tell us everything." He almost chuckled.

"To where?" said Will.

"Yes." Mrs Traynor's voice had a faint edge to it. "Do come, Louisa."

"Come with us," he said. His voice was gentle. "Don't go, Clark. Please."

I realized what he was saying. I didn't really have anywhere to go.

I wanted to cry then. But I knew with utter certainty that I couldn't be anywhere near him. "No. Thank you. I hope you have a lovely meal." I hoisted my bag over my shoulder and, before anyone could say anything else, I was walking away from them, swallowed up by the crowds in the terminal.

"No." I swallowed, tried to raise a bland smile. My sunglasses were a shield. "Thank you. I'd really rather get back."

"I'll go to my parents" house. It will be fine."

I turned, and she was forcing her way through a coach party, casting the backpacking teenagers aside like Moses parting the waves. The airport lights were bright on her hair, turning it a kind of copper colour. She was wearing a fine grey pashmina, which draped artistically over one shoulder. I remember thinking absently how beautiful she must have been, only a few years earlier.

"Stop. Louisa. Please stop."

I was almost at the bus stop when I heard her. Camilla Traynor, her heels clipping on the pavement, half walked, half ran towards me.

"Please. Please stop."

I stopped, glancing behind me at the road, wishing that the bus would appear now, that it would scoop me up and take me away. That anything would happen. A small earthquake, maybe.

"Louisa?"

We didn't speak.

"He does look well. Very well." She stared at me, standing there on the pavement. She was suddenly acutely still, despite the sea of people moving around her.

"He had a good time." My voice sounded clipped. Oddly like her own, I found myself thinking.

She went pale then. I saw the colour drain from her face, the way she swayed a little in the morning sunshine. I saw Mr Traynor coming up behind her, his stride brisk, one hand holding his panama hat firmly on his head. He was muttering his apologies as he pushed through the crowds, his eyes fixed on me and his wife as we stood rigidly a few feet apart.

And then I said, "Mrs Traynor, I'd like to hand in my notice. I can't… I can't do these last few days. I'll forfeit any money owed to me. In fact, I don't want this month's money. I don't want anything. I just --"

"I'm sorry," I whispered, so quietly that she could not have heard me.

"You… you said you thought he was happy. You said you thought this might change his mind." She sounded desperate, as if she were pleading with me to say something else, to give her some different result.

I couldn't speak. I stared at her, and the most I could manage was a small shake of my head.

He was almost there as she fell. It was as if her legs just gave way under her, and Mr Traynor's left arm shot out and caught her as she went down, her mouth a great O, her body slumped against his.

His hat fell to the pavement. He glanced up at me, his face confused, not yet registering what had just taken place.

And I couldn't look. I turned, numb, and I began to walk, one foot in front of the other, my legs moving almost before I knew what they were doing, away from the airport, not yet even knowing where it was I was going to go.