If you’ve put up with someone for 36, it’s far too late for a divorce. Kiss and make up.
Who knows what the reality is, but this likely won't end well for him. No one knows him like she does, and no one ever will - even if he thinks ‘she doesn't undertand him’. The sad truth is that the world is full of acquaintances, and few people who actually truly know or care about you. Life is that way, and we are all struggling in some manner or another.
Having said that, my parents were married for over 50 years when my father died, and my mother couldn't be there emotionally for him. It's a long story that doesn't matter at this point, but suffice it to say that I also understand how a long marriage can also be an ongoing empathy shell. Sadly.