If he is not a sexual person, this will not change.
Some people just do not want sex. They can be affectionate, loving, nice people who just do not want sex.
If sex is something that is essential to you - and it sounds like it is - please consider leaving him.
I don't say that lightly, honestly I don't. I don't think there is anything wrong with not wanting sex. I think it's a perfectly valid choice.
I think it is 100% wrong to attempt to force another person into a celibate life with you.
It's not about the spasms because let's be honest, you can do that yourself. It's about the closeness, it's about sex= being loved and wanted.
It destroys you when the person you love does not want to be intimate with you. You look at yourself for reasons why. If only you were prettier, slimmer, more this more that, then he'd want you. You wonder if he's getting it elsewhere, if you revolt him, you wonder if he's gay, you go through hell.
Then you give up. You stop caring. It stops being an issue to you because you let that part of you die. Somehow that's worse, I guess but at least you don't cry yourself to sleep any more.
Don't let this be you in 20 years. If he won't work with you, won't see a doctor, isn't interested in a sex life, then let him go. It is more painful to stay than to go.