A recent investigation into the causal relationship between marriage and life satisfaction found that people who regard their partner as their best friend derive more satisfaction from their marriages than others.

Photo Credit: Nathan Congleton via flickr | CC BY-NC-SA 2.0

How much more life satisfaction are we talking? According to the study, which was conducted by economists John Helliwell of the Vancouver School of Economics and Shawn Grover of the Canadian Department of Finance and published as a working paper (grain of salt, etc.) by the National Bureau of Economic Research, "well-being effects of marriage are about twice as large for those whose spouse is also their best friend." At the New York Times, Claire Caine Miller expounds on this observation:

Marriage has undergone a drastic shift in the last half century. In the past, as the Nobel-winning economist Gary Becker described, marriage was utilitarian: Women looked for a husband to make money and men looked for a woman to manage the household.

But in recent decades, the roles of men and women have become more similar. As a result, spouses have taken on roles as companions and confidants, particularly those who are financially stable, as the economists Betsey Stevenson and Justin Wolfers have discussed.

The benefits of marital friendship are most vivid during middle age, when people tend to experience a dip in life satisfaction, largely because career and family demands apply the most stress then. Those who are married, the new paper found, have much shallower dips – even in regions where marriage does not have an overall positive effect.

"The biggest benefits come in high-stress environments, and people who are married can handle midlife stress better than those who aren't because they have a shared load and shared friendship," Mr. Helliwell said.

More analysis at NYT. Read the full study at the National Bureau of Economic Research.