When thinking of my H's mcl and my actions in my own mlc, I believe they leave without looking back because they know if they look back they wont have the courage to go; they cant handle the pain of seeing the reaction to them leaving, in a way they know they are being irrational but the pull to flee is greater than their own will. It is greater than anything. Many truly want to stay but the crisis is pulling them to experience, to explore, to run. You know when you are a little kid and you think if I run fast enough ....I can fly? I believe on a spiritual level, there is some correlation there with development and the feeling of freedom of "flying".