SEXUALLY FRUSTRATED

Ladies!!! Ik for a fact my bf isn't cheating but we've only had sex twice this year and for the whole 2 1/2 years we've been together sex has always been on his terms. I've went as far as checking his underwear. He jacks off apparently so much that when it's time for us to have sex he isn't in the mood. What's weird is that he loves me more than I love him and I've even caught wind that this year he'll be popping the question. I'm drifting apart from him because of the boring sex life. While he's loving me more and more. I've got tried spicing things up and he's always down but when the time comes he'll make excuses. He doesn't hang out with many friends. Usually me. And we're always together. We go to work then home. He loves how close we are. Idk what to do because I'm so tired of talking to him and telling him I'm sexually frustrated. He knows!!! I've said it so much that he calls me a nympho. I'm human. I used to go through his phone when we first met just to see if he was cheating and I discovered he watches A LOT of porn. This bothers me because I'm ANGRY! But Ik this is not a reason to leave someone especially when I'm being treated GREAT in every other area of the relationship. Help!! Wwyd