The non-committal, emotionally unavailable man pairing with an overly attentive female who is willing to hang in there--no matter what--is a surprisingly common relationship. Always eager to sew wild oats, the male in this dynamic is frequently described as a "player.”
Why in this scenario does the female stay true to such a man? It may be because she believes his very aloofness makes him a more desirable catch. If she hangs in there long enough, he will eventually commit, and it will mean so much more because he was so ambivalent about her in the beginning. She sees a chance for self-validation in earning his attention when others couldn't.
Women caught in this circular thinking rarely experience a happy romantic ending.