I think it is used as a temporary way to save your sanity. Sometimes people, especially women, don't have a way to get out of the relationship. Sometimes they need to save up money, or need some time for their plan to come together. This is a means of mental survival until you can get out.
Originally Posted by
DontRemember 
I have to ask; why would you,me or anyone put up with that 'level' of a relationship?