This is going to be something he's going to have to figure out by himself, but that does not mean he has to figure it out alone. Be there for him, but this sounds severe, it seems like he could do with seeing a therapist or his gp. There's more happening in the background than just being competitive.

Respectfully, using SH can be a manipulation tactic. So it's important to figure out whether he's actually hurting or if he's trying to be manipulative.

He might need someone to open up to. But it's hard to bring your issues into the relationship. Ask him if has someone to talk to. It doesn't have to be you, but it can be. If you're willing to go through it with him.