Unfortunately for my mother, her parents refused to allow her to call off her engagement to my father because they did not want to suffer the embarrassment it would cause them. My parents' marriage was miserable from the outset, even though they remained married for over 20 years.
We always have the right to feel whatever we feel. We also have the right to express anger when we feel hurt or betrayed. However, the real question is not whether you have the right, but whether or not your anger is working for you.
Though there are no statistics specifically addressing how many long-term married couples consider themselves happy or actively in love -- it would be difficult to assess -- there are other facts and statistics to support the claim many remain together obligatorily ever after.