Engaged and in trouble
I recently (~5 months ago) got engaged to my boyfriend of 5+ years. It was so perfect and wonderful and we were looking forward to our life together! About 2 weeks ago, after yet another failed attempt to have sex, we started talking about it and he admitted being unsure if we should get married. Our sex life started GREAT and remained that way for the first 3.5ish years (we've been living together for about 4.5 years) but this past year, it's been infrequent (1-2 times per month) and whenever we try, he rarely finishes. He gets and stays hard, says he's attracted to me, it just "isn't going to happen" or "doesn't feel good". It's hard to hear that, I feel like a failure. I've gone to the doctor, meditated, tried introducing toys (he's been resistant), lube, different positions. He doesn't get off when I give him oral either, never has. Says I'm not good at it.
Our marriage is on the line and I don't know what else to do. I want to marry him, more than anything, but this one aspect, albeit critical, seems to be the only issue we have. He seems to be equating our sex life with love. Questioning if he's in love with me and if this is a good choice to get married. He's said we can't get married if we can't have sex. Maybe he's right, but it was once a good sex life, now it's not and we got engaged with it not being at its best. I guess I don't know what changed to go from good to not good.
Help. What do I do?