They may be in love:
Remember your first love? To the love-stricken teen it's easy to cave to the pressure when you think “this is the one.” You believe with all of your heart this is the person you're destined to be with for eternity. Dramatic, yeah, but remember those teen years? To you this person is trustworthy and you would do anything, and I mean anything, for them. To the teen who's in need of this type of attention or in need of love and acceptance, he/she may give in and do something he'll/she'll later regret.