@QueenoftheNights,
Thanks, but I've read the thread. Perhaps I didn't make my point clearly enough. What I read is that the OP's partner has given, in fact, a variety of reasons in response to the question "why won't you have sex with me". So, she's had her answer. She's asking the wrong question. The question she ought to be asking is "We aren't having sex, this doesn't work for me, and what are you prepared to do about it."
Unlike some, I wouldn't say "leave him" because we don't know what his response to this approach would be. I would say that if he is completely unwilling to discuss the problem, it doesn't bode well for the future of the relationship.
I have also read a lot of speculation on this thread about what the actual cause for his reasons. In my view this an enormous sideshow, and potentially harmful advice for the OP. The reasons are irrelevant. What's relevant is that he's given his reasons and, as you say, won't discuss them.
It's very sad, but even if he has suffered from abuse in the past, or suffers from ED or some kind of depression or other problem, the reality is that he has to fix that himself and the OP will probably not be able to do this. It's not anyone's job to 'fix' a person with whom they have been in a relationship for just a few months. This is just as true for men as it is for women. Unless the OP is some kind of genius, she will be unlikely to provide good understanding or support. So, the OP has no responsibility to work out what his problem is. There's nothing selfish about this - it just reflects the reality that she won't know him that well and therefore may not be able to help.
If she thinks he's enough of a good thing to go without sex, that is of course a completely valid choice but she needs to make it with her eyes open.