On our way out of the park, we passed a woman with long blonde hair, wearing an expensive-looking black coat. She could have been a model, with sharp cheekbones and huge eyes.

‘See something you liked?’ Charlie said, after the woman had passed and was out of earshot. A switch had been flicked and Charlie’s mood had changed in an instant.

‘Huh?’

‘That girl. I saw you staring at her.’

Charlie stopped walking and I was forced to stop too.

‘Staring? What are you talking about?’

‘I saw you. Your tongue fell out of your mouth. You were practically drooling.’

‘No I wasn’t.’

She moved in front of me. ‘So tell me you weren’t staring at her.’

‘Charlie, this is ridiculous. I looked at her, sure. But . . .’

‘Looked at her?’

‘Yes, but just an, I don’t know, appraising look.’

‘Appraising?’

Her voice had grown louder and I looked around, worried someone might hear. It was embarrassing. But there was no one nearby.

‘That’s the wrong word,’ I said. ‘Charlie, this is ridiculous. You’re accusing me of what? Fancying her? Planning to track her down and . . . hobble off with her?’

‘No. But you were wishing you could be with someone like her. Instead of me.’

I was flabbergasted. ‘Charlie, I think you’re the most beautiful woman I’ve ever seen. I have no interest in other women. None. I promise you. This is crazy.’

Her face twisted into what I can only describe as a snarl. She jabbed a finger at my chest and hissed, ‘Don’t call me crazy. I am not fucking crazy.’

And she started to cry.

‘Charlie.’ I leaned on one crutch, reached out and pulled her against me, which wasn’t easy, especially when she resisted. Her muscles were wound tight, her back as hard as rock. But then she gave in, relaxed slightly, letting me embrace her awkwardly. I whispered reassurances to her, told her I loved her and didn’t want anyone else. She apologised and promised she would stop being so stupid.

But I was worried. She’d shown a few signs of being prone to jealousy before, but not this level of irrational insecurity. I was certain I hadn’t looked at the passing woman with my tongue hanging out, as Charlie had put it. But had I stared at her, shown signs of desire without even realising it? I tried to imagine how I would feel if it was the other way round, if some gorgeous bloke walked past and Charlie had looked him up and down, shown obvious signs that she found him attractive. I wouldn’t like it, that was for sure. I wouldn’t, though, accuse her of wishing she was with him. I wouldn’t have got upset about it.

Then it struck me. The conversation in the bathroom.

‘I’m not like him, you know. Leo.’

She looked up me.