How to help this person?

You know the answer yourself. Your question I must so is so amazingly put. I wish I had a friend like you. He must be very special. You are so right. He may need to suffer more until suffering become too much or he may need a push ( subtle) at the right time. To be honest I doubt there is more you could do. You are an angel to him. ( If you tell him what you told us then thats mive and your conscience is left clear .)