What's wrong with him?!?

This guy's been trying to get with me for over 3 yrs and i always turned him down, about 2 weeks ago he asked me out on a date and i said yes and because i was smiling so much he didn't believe me or take me serious. before he asked me, he told me that he didn't have eyes for anyone but me and how i'm special and ****, but now i see him talking to this tall, hunchback looking girl and i think they're together. what the hell is that, can anyone explain why he did that?