I don't want to get involved with my friend's relationship issues.
Is your friend having a problem with his relationship?
His girlfriend is angry with him.
Usually, I would advise people to stay out of other people's business, especially when it comes to relationship issues. Nothing good ever comes out of it and it can ruin your own friendship.
My friend wants me to help but I don't think it's the right thing to do.
Your friend needs to work things out with his girlfriend. You can offer your support, but ultimately your friend needs to repair his relationship or end it if he wants to be happy.