Safety. Women want to feel safe. They seek out men who can protect them. Sorry, but it's true.
When a woman feels that her man can no longer protect her or their children, she has no use for him. Humor, cooking, intellect, whatever other qualities he might have become meaningless. They were only perquisites stacked atop his primary attraction: safety.
Want to know why young, beautiful women are atrracted to wealthy old men? Safety.
Want to know why young, intelligent women are attracted to ugly hoodlums? Safety.
Want to know why women leave men? Danger.
If a man fails to make his woman feel safe, he has failed in primary purpose as a man. Nothing he can ever do will restore that safety, and any pretense of a "relationship" thereafter will be a sham.