It's simple. People get married because they are happy and they get divorced because they are "unhappy". Simple as that. Both the happy and unhappy state are "states of mind". While we might like to deny it, it is one of the few things that we fully control. So, if we are in the unhappy state, that is something that you actually "control". What this article shows is how all our "expectations" are what is leading us to the unhappy state and perhaps if we could just change our expectations, then we could get back to the "happy" state.