Exactly, there is a big difference between duty and stupidity. To stay in a horrible marriage (sans children etc) just out of 'duty' mocks marriage- making it into a nasty, vile trap where once you go, you are punished for every sin ever committed.
I am widowed, but I do understand the hell of a very bad marriage. My parents didn't divorce, I wish they had. A bad life is a bad life, no matter how you try to dress it up.
My parents got divorced when I was 14. I can honestly say it was better for everyone involved, including me. Actually, the only one who did suffer was my dad, but he had it coming to him. If he would have cared as much about my mom before the divorce as he did after, it would have never happened.