Sorry but not posting this in the men forum as it says 'men only' which I don't agree with - women feel free to offer your perspective too even if the question itself is to guys.

When I was married I had big problems with sharing a bed because I tend to startle easily when touched, and this not only made it hard to sleep but occasionally I would instinctively push my partner away, especially if I was half asleep when it happened. Over time I also found myself getting more closed down sexually and didn't want to be touched or have sex, but sometimes if I was asleep I would find myself waking and having sex without having initiated, apparently because I responded physically to my wife's touch while asleep enough to get aroused (possibly I was having an erotic dream too?) and I guess she 'climbed on' thinking I was present when I wasn't - but then when I woke up and sort of found myself there my instinct was to want to push her off because I didn't really want it and it was quite scary actually but I couldn't do that without hurting her so just went along with it but since I wasn't into it really I would fake coming to bring things to an end on my part without making her feel bad, or sometimes then focus on helping her come too if that was still needed.

I always thought that this was pretty rare for guys but I have read recently that it's more common than was thought and that it's a bit of a myth that guys can't fake orgasms because of the link between orgasm and ejaculation but actually that is not the case.

btw this is one reason why I don't like to sleep regularly with women as I get afraid of sharing a bed and these things happening again (even though paradoxically I do miss the intimacy of sex on an emotional level but I need it to be very carefully paced and a lot of people don't know how to do that).