Help with a boy please? elastic band theory ?

Could be the elastic band theory or he's dissapointed that you liked him and he saw it but didn't do much out of the ordinary like u didn't ask him out but he didn't either.he could have a gf to and he didn't tell u.if he says your pretty your pretty stop putting yourself down.and how old are you?I'm in 8th grade hope it helps oh and I'm straight.