Its not really a "crisis", but maybe an epiphany. Society forces to think we want to have a spouse, 2 kids a big house with a giant mortgage and whatever else. Maybe it just takes some a long time to realize that isn't what they really wanted and need to act quickly to change. I'm not saying this is the way to go, but a woman cannot begin to explain how a man thinks, nor can a man begin to explain how a woman thinks.
A mid life crisis is considered a legitimate thing, more than just a colloquialism. If it's a mid life epiphany, it is not called a crisis...the person would leave the family for the new life they realize they want. Very little crisis involved for that person (just for the family left behind). A crisis is that chaos, not knowing what one wants or needs; taking wild stabs at finding it.
I disagree with the last sentence though, really limits the reality of human understanding.