What a sad situation! It seems that Nancy may be depressed. It seems your reasonable request to have her compromise 33% of the time is a healthy one. I hope you can get through this. I do think couples counselling could be helpful here - because it seems this is more a relationship problem of her not thinking your needs matter as much as yours.

Also, it seems maybe she could be trying to push you away, because she fears you leaving, and so wants to be able to control when it happens subconsciously?

There's a type of therapy that wouldn't require an external therapist, it's called Internal Family Systems, and it can be done together using some books from Amazon. My husband did it and it was lifechanging for him.

Essentially IFS states that there are different "parts" of a person that develop in result of trauma, these parts often want different things that may be in conflict because they developed at different times in different contexts.

Nancy seems like she might have a "part" that is trying to push you away, and a "part" that wants to be a loving partner. A "part" that wants to give up and rot, and a "part" that wants to enjoy life (but is afraid of losing more if she tries something but can't do it). Perhaps a "part" that prefers the fantasy of the activities that "might be possible later on" vs the cold truth of an activity that she tries but finds out she's incapable of doing.

IFS helps one untangle the different parts and helps you to align them so that you're aware of when you're engaging in self sabotaging behaviours. It helps you realise what you really want and how to get all your needs met.

Even if Nancy doesn't want to do it, I would recommend it to anyone, even to you, because finding out your hidden needs and motivations is valuable for everyone.

I wish you both the best and I think you're a very caring husband in a tremendously difficult position.