[2BNTV]

I was wondering if the great minds of this board could answer this question.

A family member was a caregiver to both her parents who are in their ninety's. They were recently put into a nursing home as she could no longer do this anymore. One of the parents refuses to go for medical treatment needed outside of the facility as he doesn't want to be away from his spouse. No family member can convince him that his decision is not correct.
He would rather pass away rather than leave her for a short while.

When people reach the eighty's and ninety's, why is their point of view so intractable?