Early research on marriage and happiness has uncovered a positive association between the two. This so-called "marriage advantage" showed that, on average, married people tend to be healthier, live longer, and be at less risk for many serious health conditions than those who never marry. Marriage also tends to reduce the risk of depression and anxiety.
However, like most things in life, it's not as simple as black and white. Newer research studies further qualify how the quality of the relationship affects a couple's individual happiness and health. Not surprising, people in troubled or unhappy marriages tend to be much less healthy than their single counterparts, while single people are healthier than those who married and later divorced. Researchers have found that when married people become single again through divorce or death of a spouse, they suffer a decline in physical health from which they never fully recover.
Everyone has a set point for happiness. We gradually return to that level of happiness even after very positive experiences, such as getting married. So while we may get a happiness boost when we marry, we'll eventually return to our level of pre-marriage happiness. It works both ways. Five years after a very negative event, say divorce or death of a spouse, we're back to our preset happiness level.
In a 2010 Gallup World Poll, which measured two categories of happiness-overall life satisfaction and moment-to-moment enjoyment of life-researchers found that while overall life satisfaction is strongly tied to income, moment-to-moment enjoyment was more dependent on having one's psychological and social needs met.
Emotional security and companionship are the strongest features of romantic relationships that predict happiness. Furthermore, people who've been in a long-term relationship tend to develop what's called emotional convergence. In other words, over time, they come to have similar emotional reactions. This phenomenon is beneficial to both friendships and romantic relationships, making them stronger and long lasting.
The bottom line from all the research on happiness and marriage is the same: it's the quality of the relationship that matters, not the institution of marriage. Having a supportive relationship in your life is more significant than being legally married.
If you are in a difficult relationship, you are generally better off trying to improve the quality of that relationship than ending it. Remarrying does not have the same health and happiness benefits as maintaining a strong relationship in the first place.
Sources
Becker, Anne. "Marriage is not the key to happiness." Psychology Today. Web. 23 January 2009. http://www.psychologytoday.com/articles/200303/marriage-is-not-the-key-happiness
Sahelian, Ray M.D. "The Intelligent Pursuit of Happiness." Web. http://www.raysahelian.com/happiness.html
Parker-Pope, Tara. "Is marriage good for your health? New York Times. Web. 18 April 2010.
http://www.nytimes.com/2010/04/18/magazine/18marriage-t.html?_r=1
