Interesting topic, because I know that historically, culture and religion had a lot to do with whether or not divorce was acceptable for a failed relationship. These days, I believe that it has become much more acceptable, in places like China and others. In my country, the USA, religion and family values has a large impact on the acceptance of divorce. For example, my grandparents were married for 70 years. But my father was married 5 different times.
For my grandparents, religion was very important to them (they both passed away last year) and within their religion, divorce was not an option. My father, who was not religious, married very frequently, and just as frequently, divorced.
I myself, have been divorced, a long time ago, and chose to raise my daughter on my own, because I could provide a better/safe environment for our daughter. I have not re-married, because I have chosen to make marriage something important, and to not treat it as a recylceable item, so I have waited for the "right" person.
Of course, people should also consider the other circumstances, are there children involved etc. Ultimately, I believe, if two people are not happy together (it doesn't mean people are happy 100% of the time, that is not realistic), they need to make the right decision for both themselves, and if they have children involved, for their children. Marriage is important, and every step should be taken to preserve it, but ultimately, we are put on this earth to enjoy it, and to enjoy the relationships we are in. It always comes down to the choice of the individual, they are the ones that will have to deal with the consequences.