I think that those who walk away are never really satisfied with anything, ever. They are constantly trying to fill that vacant spot in their black souls, but they don't realize that whatever they are searching for, they will never find.
I third this. I remember one of the few serious fights I had with my STBX years ago. I remember telling her angrily, "You are a bottomless well. I can pour and pour for the rest of my life and you will not be satisfied. There is something in you that will not be satisfied. You have placed me so high on a pedestal as The One to undue everything you went through in your life that if I ever waver, to you I will have toppled off this pedestal. That is too much of a burden for me and unfair."
I was proven right. Nothing could fill the void and she walked away looking for the next thing. Now that I look back at it, even if I'd been the perfect husband (whatever that means) it was inevitable. She would have cheated and she would have left me.
But goddam her, I still miss her ( who I thought she was) especially when I am having fun and loving times with our children and her "chair" is empty.