Some of the reasons why some people are unlikely to leave an unhappy marriage include:
1. Fear that the changes divorce brings will be worst than the current situation.
2. “For the sake of the kids”.
3. Determination that they can fix their spouse.
4. Need to prove that they can deal with a tough situation and survive.
http://divorcedmoms.com/articles/4-reasons-women-dont-leave-an-unhappy-marriage