He's driving me crazy

Before I got pregnant, I'm 30 weeks now, my SO and I had a great sex life. It was everyday and amazing, but now over the past two months he won't do anything with me. He'll touch me sometimes but he's fine with watching porn every single night after I'm asleep, but I would lay there ready to go and he can't. He can't get hard with me, all he says is "it's not you, you're so beautiful, I promise this is isn't because of you", but what am I supposed to think. I'm just so frustrated I just want some lovin already.