GUYS ANSWER girls can too but it might not be as good advice.?

there is this guy. he has ased me out. but at the time i didnt like him. but alo at the same time he had a gf. he still likes me. like him now. but his gf one of my BESTFRiENDs goes wiff him. they kiss right in front of me. but still he likes me. i was instanlty depressed.. still am. i have dreams about him sometimes. OMMG whywould he do that.