My boyfriend doesn't want me?

So me and my SO have been dating for a while. I'm at his house constantly (ive been here for like almost 3 weeks now.) But lately he's been different.. in the 3 weeks I've been here we had sex ONE time. And we always used to have a great sex life. It just seems like he's not interested in anymore. Everything else is important, except me. I've talked to him about it and he tells me I'm not his priority. What do I do? I love him, and he says he loves me.. I'm just confused and lonely. Just lost.. it hurts so much to think he doesn't want me or I'm not good enough for him. Advice?