I was talking to a friend yesterday who has been in a relationship with a man for over 20 years and what she said yesterday is almost the same as what you said. "...at a loss to confront him when it is so difficult to get him to appreciate any viewpoint other than his own".

I feel helpless to know how to support her especially when she is trying to negotiate acceptable outcomes in one-to-one conversations with him.

It is good that the people around you are supportive.