He can't stand his best friend. Dunno what to do

Tell him straight up: "Youre hurting your best friend." Have ahandwritten letter explaining why, so he can reference.

I'd stay out of it. You're relatively new on the scene, and probably don't understand all the nuances of their long relationship. He may have a very good reason to distance himself from her, and that reason may even include his relationship with you.

Very few people would have done the things she did for him without wanting to be with the person they were helping, so he's probably right about her motivations. She definitely had a choice to help or not, no matter what she might have said to you.

You may find this man lazy and immature, but truly stupid Gems are few and far between. He probably knows exactly what he's doing and has reasons for doing it. You don't need to hold his hand and explain with picture books. I'd trust him to deal with his own relationships and, instead, ask yourself why it bothers you so much. That's really the only aspect of this scenario that's truly yours to deal with. .