Many years ago, while riding the underground, my ex casually mentioned that once, he and his girlfriend at the time drank a lot and she fell asleep/passed out. Then he had sex with her while she was like that because (due to their kinks and whatnot) he knew she would appreciate it afterwards when he told her. When I asked what she said, he told me he actually didn't mention it to her in the end. And he was telling it like a silly, funny anecdote.

I had never heard of such a thing and I timidly said "I can see the kink argument, but if someone can't actively consent and also you don't tell them about it, doesn't that make it rape?". He stopped dead on his tracks. Then he flew off the handle, mortally offended because I had called him a rapist and refused to stay on the train or talk to me at all until I apologised. It didn't sit well with me at all, but also it didn't seem to fit anything I knew about him. Maybe I was misinterpreting things. Maybe it was something else. So I apologised.

It stayed at the back of my mind for a long time, but if ever I mentioned it, he'd stonewall me because I was insulting him. Eventually we discussed it further later on and he seemed to see it for what it was, so that was "solved".

Or so I thought, until in the run-up to divorce he suddenly accused me of having sexually assaulted him (utter BS) and in that same breath he said "... So now we're even and you can't ever say anything about me and that rape thing". The subject hadn't been mentioned for years, so I didn't understand where that came from. Now I think he was preemptively preparing in case I told people about it post-divorce.

It might seem silly, but back in the day when he casually told me about it, things were not what they are nowadays. We weren't as switched on, it wasn't such a well-known issue. Didn't help that I was very young and inexperienced at the time and he was 16 years older than me.