It's not easy to answer your question without knowing more about what makes you think he doesn't want to be with you.
The problem comes down to one of three things: either you're very insecure, he's not that into you, or you're incompatible, but you haven't described enough about why you believe this to help narrow it down.
You're feeling that way because your needs are not being met in some way. What needs are they, and are you needier than the average woman in that regard? If not, then consider that maybe he's not your ideal mate. Best wishes!