I think you need to look at your relationship. Obviously he has a libido since he had it a lot when you first got together. What's changed?
Moaning and nagging someone into sex is the biggest turn off and once they give in and do duty sex with you, it's bad sex and they associate sex with you negatively and begin to dread it. So stop that.
When we first get into a relationship we present ourselves as best we can. We take care of our appearance, take care to have fun with the other person, to treat them well, listen to them, respect them. We have to be on our best behaviour and present well because otherwise they'll be out the door. Once people settle into relationships and get comfortable they tend to forget those things, sometimes they go in the opposite direction.
So why doesn't he want to have sex with you? What is different now than at the beginning when you were having loads of it. If he met you today for the first time, would he want you? If you behaved when you first met as you do now would he have stayed with you?
I've only ever had one relationship where I didn't want to have sex after a while and the reason was him. His hygiene and appearance changed, his manner of speaking to me became rude, he never listened, which turned me off initially. Then came the constant pestering which led to what I used to think of as torture sex which I only did to shut him up. Then you really don't want to be near him after that...
I don't think men are much different than women tbh. Men can be just as turned off as women can if the relationship is going badly or if there are issues which a putting him off. They're not all robotic sex machines.