Sometimes having a dysfunctional family is the only option, I've personally seen many relationships in which I though getting a divorce was a good option but they still keep at it, fighting at every given opportunity but never getting a divorce.
Cheating on each other but not letting go of that relationship just because they fear the society and also don't want their kids to go through with their parents divorce.
It must be hard to live in a relationship like that but that's where they find their peace just because they fear, things might get even worse if they take the next step.