Most Helpful Girl
Firstly if your girlfriend does not respect the fact that its bothering you then she is enjoying the guys attention and that's not a good sign and secondly you should talk to your girlfriend not the guy... she needs to tell him its not ok. its not your job... he won't listen if you tell him only if she does...
Most Helpful Guy
Who is the guy? A friend or family member? Dump her, if she won't tell the guy to stop it then there is some thing going on with the guy sending hearts.