Most Helpful Guy
Avise her, tell her what you heard. If you don't and she get involved with him, things are gonna be much worse.
Most Helpful Girl
''she keeps having her eyes closed'', she doesn't want to admit, to face it that her crush is THAT type of person. In my point of view, you should keep warning her but don't try too hard, she may feel irritated or even ''push you away''. If you could say to your friend John talk to him (if they're friends maybe) and convince him that this is not right it could help. Otherwise, if you know that Gina and that boy are hanging out somewhere specifically, why don't you try to go out with your best friend and ''incidentally'' see them. This would definitely open her eyes. For sure. If she stills doesn't get it, stop saying things for him. I know that you'll still bother and care about your friend's psychological health and her emotions but hey, just do it. Because you tried, you really did. And she just didn't want to listen. But after this boy has played and dumped her, who will be there for her? You, only you. And yes, she will break down and cry but then she will realize that you were the one that advised her not to associate with him and mainly the one that for sure cares about her because you will be the cry shoulder. She will appreciate all this. But see it as the last resort, of course. Try the first options. Hope I helped;)