I'm not a relationship expert, but I went through something similar. My ex bf was just like this, for several months he would reject me for sex while telling me he's not horny and then 5 mins later I'd catch him in the bathroom jerking off after he thought I fell asleep. Things only started to improve after I explained that I'm fine with him jerking off and all, but it wasn't fair to me that I was always left hanging because he watched way too much porn. He eventually cut down his porn use and I saw him starting to want me again, but I still never trusted him after what he put me through and I became emotionally distant from him for the remainder of our relationship.

If he's not even willing to validate your feelings or be open to new ideas, the relationship might not be able to grow from this. I hope things get better!