Why did this happen:'(?

ok heres the thing...i went downtown today with my girlfriend.im 16 and shes 15 btw. downtown there was this hippie guy talking about peace and stuff(with short hair).so i was sitting with my gf and we wer talking with him...my gf was drinking alot of alcohol and i told her to stop but the guy said like let her take her own decisions.he is a 23 year old btw that hangs out with 14-17 year olds at night.after a while my gf said she wanted to piss kind of directing her voice to the guy.and the guys like said ill show u where to go.i was STUPID IDIOT i just sat there while he took her into a toilet in the restaurant.i trusted this guy cz he was like very peace ful sociable and a knowledge person so i didnt mind...after i thought of it better i ran to find my gf.i went into the girls bathroom and i tried to open the toilet door.somone was standing infron of it so it wouldnt open.i called her and she said shes coming out.i went out of the toilets and then she came out and i asked her: