Should i have tryed to get with him?

well i used to like this. last year we had the same cl together and i was gonna try to ask him out but, a few days later i figure out they have a girlfriend so about a few months later his girlfriend gave me an ugly look then she started dressing skimpy i don`t know why she was trying to make me jealous because i would never try to get with someone in a relationship. so about another month later she changed cles. so i was uming maybe they broke up because he was getting flirty with some of the girls in cl and having with a few of them. i would not go that far for him to like me but, sometimes i wonder why i did not try to get with him i was also concerned about the age difference he is 19 and i am 16.