Fiancé says he has low sex drive?

My partner is 26 and I’m concerned with some things going on. He says he has low sex drive but honestly he has avoided a doctor for a year now I have tried to be there and help him out but I’m at a loss. One of the first things people tell you is to communicate and try to help but where do you go if the other person won’t. I’m just scared he isn’t interested or attracted to me anymore and just won’t tell me. It is hard because our relationship is starting to feel more like a friendship.. I do love him but it’s super confusing on why he won’t put the effort in to help us? Now my mind wanders from “is he lying about it.”? He is loving and all the other things but that is it. Everyone keeps asking can I live with it well he won’t give me an answer or try to help so how do I know what I’m exactly living with in detail? Ugh help.. it’s hard to because I can’t talk to anyone about this situation. The one I want to talk to shuts me out and every part of me is screaming for help/affection/making love.