Is this the end?

This is so sad to think about but it has been on my mind for a while now. I've been with my boyfriend for 6 years now and I feel like spark is gone. We are no longer romantic and sensual towards each other anymore. I have talked to my boyfriend about it several times and it starting to feel like begging. I still want sex and he doesn't (which is weird). Maybe, he's cheating on me again. And even tho I bring it up to him nothing changes or I don't get a legit answer. For instance, we were together all weekend and we didn't have sex once. Every time I would make a sex gesture towards him he would push me away or get up and leave the room. I starting to think it's me. I starting to he's not into this relationship anymore. If he isn't I wish he would say something instead of wasting my time. I think I'm also getting miserable in this relationship... What should I do???