Most Helpful Guy
Okay, I would not bother with this guy. He sounds like he actually needs serious help and I doubt you or your friend are qualified to do that. He cut himself because she talked to another guy? That's going overboard and he also has no trust in his girlfriend at all. He's proving that by not allowing her to do what she wants. I understand if he gets jealous and doesn't want to lose her but he can't control her life like that.
Honestly, I say get rid of this guy. He sounds controlling and he also has other problems which he needs to seek help for.
Most Helpful Girl
Maybe work with him to find a passion in life or a hobby. You can't always focus on begin with love. He seems to have anxity of begin alone or dumped. I suggest he talk to someone!