He walked into the room, came up close. His breath stank of warm lager and I shrank away as he grabbed my arm and leaned in close, his nose inches from mine. ‘Do yourself a favour, mate. Don’t let her move in. Get away while you can.’

I pulled my arm free. ‘Why are you saying that? A minute ago you were saying you’d do anything to spend another night with her.’

‘Yeah. A night. Not a day.’ He pulled up the sleeve of his jumper and I gasped. The skin was criss-crossed with slashes, most of them scars but some fresh, scabbed over, the skin between the knife-marks looking like it was going to peel off.

‘See this. This is what Charlie did to me. She fucked me up.’ A noise came out of his mouth that was half laugh, half sob. ‘She really fucked me up.’

I waited for him to calm down.

‘What did she do?’ I asked quietly, dreading the answer.

He sat down on the edge of the mattress, picked at one of the long scabs on his arm. ‘It’s hard . . . it’s hard for me to talk about. But you know her. You must have seen it. Signs, at least.’

I didn’t want to give anything away. I had no idea if I could trust him. And with the conflict raging inside me, the internal war between virus and antibodies, I didn’t want to say anything negative about Charlie. I was still hoping that, any minute, the lights would come on and the truth would be illuminated – the truth being that Charlie was innocent of everything but being jealous, that this guy was a liar or a nutter or both, and that my girlfriend and I could get on with our lives. Walk into our bright future together.

‘I’m talking about how possessive she is,’ he said. ‘How jealous. Even though I never did anything to make her jealous. Christ, why would I want to look at other women when I had her? It didn’t make sense. I used to tell her, it’s irrational, illogical. Stupid.’

‘What was her reply?’ My throat was so dry I could barely get the words out.

‘That love isn’t rational or logical. That it’s meant to be like this: like a tropical storm, a hurricane. Exciting and destructive and unpredictable. She said that when two people love each other they have to give themselves completely. It has to be all or nothing. No one else is allowed in.’

I wondered if this conversation was awaiting me in the future.

‘She hated me seeing other women. Being in IT, I mainly work with a load of greasy blokes, but I have female friends, acquaintances. Charlie went mental if I so much as went for a coffee with them.’

‘How long had you been together when she started being like that?’ I asked.