@Pemba
That is a very good question, I've often wondered why. How can you relax and enjoy yourself knowing your partner is just putting up with it, or worse is coerced or even being raped? Can't imagine a woman doing that. Although it may happen of course, but not typical.
Unfortunately it seems that many men have a sexuality that is very different from the female one. Hence all the rapes that happen etc. It's as though desire is mixed in with a power thing? Just thinking aloud. Of course it is.
There are decent men, sadly not as many as there should be.
Excellent question. FTR I can only speak for myself, albeit as a man, but not for 'men'.
If my wife was very clearly conveying that she has zero interest and she isn't enjoying herself at all, I certainly wouldn't want to have sex with her. After all, it's not just the orgasm that I'm after (can easily take care of that myself), but the intimacy.
That said, if it isn't a case of her actively being not in the mood, only she's not 'yes' in the mood, I would expect her to sometimes make an effort to either put herself in the mood or pretend to be in the mood. Not every single time, but also not never.
Much the same as I do many things for her (not only sexual) graciously and with a smile on my face, even though I couldn't necessarily be bothered doing them. And I don't actually resent doing these things. Au contraire, I enjoy doing them not for their own sake, but because I know it makes her happy.
Basically what I'm saying in a good relationship, each spouse goes out of their comfort zone to make their partner happy. This is both something that happy spouses do for one another, but also something that can be expected from them.
If this is true generally, in my opinion it is even more true when it comes to sex. For unlike every other need or want, sex is the only one that can't be fulfilled except with the spouse.
If my wife would never want to cook me a good meal, I could always buy one. If she never showed interest in any of my hobbies, I could find others who are interested.
But the basis of LTR is sexual fidelity, meaning the only one who can fulfil each others needs/wants is the other half. Which is why I find the MN of 'I don't owe him sex' mind-boggling. If you expect him to only have sex with you, then actually you do owe him sex. Not at any given moment, and not at any specific time/interval. But conceptually you do have that obligation.