The most potent predictor of being happily married is being happy before you marry. Marriage does not make you happy, although the prospect of sharing life with a loved one can provide motivation to make yourself happy. What marriage certainly offers is someone on whom to blame your unhappiness.
— Steven Stosny, http://www.psychologytoday.com/blog/anger-in-the-age-entitlement/200905/marriage-and-the-power-be-happy