umm... well, from what i can see, the boy you liked just made a glitch (right?) or a scratch in a relationship...
coz y'see, if he really likes that girl, he would first try to figure out if she has a boyfriend already... but if he doesn't... it's the girl's problem... if she has a boyfriend already, she shoudn't have allowed the boy you liked to kiss her...
that's just my opinion, though....