Sending you love. That must be a confusing and horrible place to be in.
I agree with the above comments, analyse the rest of your relationship, is it just this part that is lacking? It might help you to make a decision if you think of the pros and cons.
I'd like to add that all relationships go through phases though, as soon as I put on weight, I dont want sex at all, if I'm stressed, sad, PMS ing, I want to wrap myself in barbed wire and beat husband off with a stick.
He has gone through a couple of phases of depression and anxiety and has taken medication for them. He says he has a non existent sex drive during these times, not sure if it's the feelings or the medication. But both of you might go through things that kill your sex drive for a while, the important thing is that you work it out and find a compromise or solution.
Either way, like others have said, it needs a serious conversation. People go through all sorts, and your partner is supposed to be the one you go to for help. There might be something really troubling him, he might need your support, he might take a while to open up, but If hes not willing to have an honest conversation, maybe you deserve better.
huge love to you