It's easy to say. First, let your friend try to make peace with him and ask him if he did anything wrong. It would be better if he accepted it. Second, first come, first served. If he remains the same, your friend will leave him. Don't be discouraged yet. Let your friend try to separate him from her, and you will regret it. Then it is necessary for your friend to fight for it, to envy it and to pursue it! Only you can think of the right way.