People are like sand in your hand. If you have sand in your hand, the tighter you close your hand, the more the sand will seep out from the sides!
His attraction for you is probably at a low. The first thing I would do is to stop pressuring him or persuading him to sleep with you. Guys DO NOT like to be pressured because it starts to feel like nagging.
Now I know I may get some hate comments for this, but as a man I will tell you how it is. Try to make yourself more desirable and attractive. Men love to chase. When something is too easy, we lose our attraction for it. At the moment you are making it FAR too easy for him, which is why his attraction for you has decreased and he isn't bothered about sleeping with you.
Start going out with your friends more, let him see very clearly that he is not the only thing in your life - men are incredibly attracted to strong confident women who have a life of their own.
Work-out, if you think you're not in shape or you think you haven't been paying as much attention to your physical appearance or personal hygiene lately (don't take it the wrong way, some people really do let themselves go and don't even realize), try to work on that.
Men and women both have different needs. Personal needs, but also needs in terms of our gender. Women love to be made to feel special by their man, chased, and above all, DESIRED. Men on the other hand, love to chase and love a challenge. Up your attitude a bit, make the best out of your appearance, make an effort to look and smell good - let him see you going out looking beautiful with your friends - and tease him sometimes. ABSOLUTELY DON'T be too available all the time, it KILLS the attraction.
The way you communicate with him is also absolutely critical. How you speak, what you say, HOW exactly you create sexual tension and anticipation and how you do this in such a way to make him desire you. Be a challenge, a flirt, a tease. But don't over do it. Mix it up.
Best of Luck
Beverly Hills, CA