Low sex drive

My boyfriend has no drive to have sex at all. We will go like a month without having sex and it drives me insane!! Literally Im reaching my breaking point because I don’t know what to do. When we get in bed he’s laying on his stomach so I cant really even try to initiate anything. And He falls asleep in the blink of an eye. Nothing seems to turn him on and It truly makes me feel like he’s not attracted to me. He’s told me before he thinks something is wrong with him, but refuses to go to a doctor. I just told him how i felt & he brushed me off and got defensive. Which I understand its a sensitive topic for him but I can’t go on like this. We’ve been together 2 years, broke up for 2 years & now we’re another 2 years together. We have a house together, talk about having kids & getting married all the time. But I don’t know what to do honestly please give me any & all advice.

*edit* his sex drive used to be high & we would always have sex at least 2-3x a week. But the past year- year & half has been very low