Help Me

So my boyfriends always plays with me sexually and he's always popping boners but when we start getting closer to having sex he just stops and either gets outta bed or rolls over and falls asleep (like teasing). The first 100 times he did it was fine but now it happens every time like he does but doesn't want to have sex. When I mention it to him he puts the blame on me. I don't know what to do or say to him anymore. What would you ladies do? What do you ladies think is going on? Could this be a sign of cheating or he just doesn't want to have sex with me?