If this woman is like the Glenn Close character, she will not be able to force affections from him. I think he honestly stated what he is finally seeing. What he is truly missing is adult affections for someone who can return the same.
She may try to make their R a drama mini series. He already told you that is no longer his idea of a R. Unfortunately for her, he just ended a long lasting M. It will be much easier for him to end a brief A. It may be a lot uglier, but that will only work in your favor. It will reinforce to him what was wrong in his life, and what was right. Be the friend, not the judge. He will render his own verdict well, once he has had his quiet time to reflect.
No one can promise what will happen next. But I do think he will make better decisions for himself. You will have to do the same for yourself. Take all the time you need whenever presented a fork in the road. Best wishes.