I can't enjoy sex with men because I feel it's degrading

Hm, that's it, that's the gist of it. I have been only with my boyfriend, have been together for six years, I'm 26. The first three years were very difficult sex wise & but also experimental, I think it would be safe to say I didn't enjoy that part of our sex life too much. Around the fourth year I had a moment I bounced in the positive direction which meant feeling ok during, before and after. Now I'm back to square one, I get zero desire for sex. My bf is very LL so it's not that big of a bedroom problem (otherwise it would be disastrous for a relationship), so we have sex around once a month. I mostly "endure" it and fake enjoyment but tbh I feel like shit for it because I know he'd feel bad if I told him I'm forcing myself. Any ideas how to get out of the mindset? I know all the talking points (regarding how to stop feeling like this) but I just don't believe in them. I love him but if I were single I'd definitely be celibate.