Help advice

My friend is 16 years old and totally a responsible person! She just one of those goodie two shoes I can't even explain. Well recently we hung out at the mall and she got a guys number who we found out after is 19! They've been talking and hanging out ! I'm worried about her ! He wayyy to old for her and honestly it's gross ! I talked about it with her and all she brought up was how I do things bad like drinking and partying ...which isn't fair I'm trying help her out and she flips it on me. She suppose to be the good friend!