If you want to be happy in your marriage, what's the most important ingredient? Everybody (married or not) has a theory about what it takes to live happily ever after. You can divide them, roughly speaking, into three different camps:

#1: It's about YOU.

Some people, the theory goes, are just destined to be unhappy in their relationships. Perhaps they are too insensitive, too negative, or too emotionally unstable - - whatever the case may be, and no matter who they end up with, they will never know real marital bliss because their own personalities will always get in the way.

#2: It's about YOUR PARTNER.

Others believe that being happy in your marriage is all about choosing the perfect Special Someone. Before I got married, I heard this a lot. "You need someone emotionally mature," or "a guy who pays attention to the little things," or "a husband you know you can always count on." According to this theory, whether or not you are satisfied in your relationship isn't so much about you, as it is about what the other person brings to the table.

#3: It's about how SIMILAR you and your partner are.

Birds of a feather flock together, as the saying goes. (Presumably, they are happy about this arrangement.) Some people will tell you that the key to marital happiness lies in the similarity between your personality and your partner's. Dating services promise to match you according to key "dimensions of compatibility," arguing that people who are more alike should end up being happier together. Judging by the popularity of these services, this theory has a broad intuitive appeal.

But who is right? Is it your personality, your partner's personality, or the similarity between the two that really matters when it comes to having a happy marriage? A recent landmark study provides us with some answers.

Psychologists Portia Dyrenforth, Deborah Kashy, Brent Donnellan, and Richard Lucas looked at over 10,000 couples from three countries (Australia, England, and Germany) who had been married on average about 23 years. Each husband and wife had completed a version of the Big Five personality inventory, which measures the five traits thought by many psychologists to make up the core of a person's character: Emotional Stability, Agreeableness, Conscientiousness, Extraversion (i.e., outgoingness), and Openness to Experience.

It turns out, your own personality is in fact a powerful predictor of satisfaction. According to the researchers, people who were more agreeable, conscientious, and emotionally stable reported being significantly happier in their marriages. So if you are a sourpuss, selfish and irresponsible, and have a tendency to fly off the handle, your chances of finding marital bliss are not good. [But remember, personality is far more changeable than most of us realize. If there is something about you that makes you unhappy, you can do something about it with persistence, effort, and possibly a little therapy.]

Your partner's personality is also a reliable, though slightly less powerful, predictor of your relationship satisfaction. And the traits that matter in your partner are the same ones that make a difference in you - - agreeableness, conscientiousness, and emotional stability. Keep these traits - - the "Big 3" for happiness in a marriage - - in mind when you are seeking Mr. or Ms. Right.

Finally, there's personality similarly - which, as it happens, doesn't seem to matter at all. The extent to which married couples matched one another on the Big Five traits had no predictive power when it came to understanding why some couples are happy together and others not. This is not to say that having similar goals or values isn't important - - just that having similar personalities doesn't seem to be.

So if you are outgoing and your partner is shy, or if you are adventurous and your partner doesn't really like to try new things, it doesn't mean you can't have a satisfying marriage. Whether you are birds of a feather, or opposites that attracted, you are equally likely to live a long and happy life together.

Just try to be generally pleasant, responsible, and even-tempered , and find someone willing to do the same.

Heidi Grant Halvorson, Ph.D.,
author of Succeed: How We Can Reach Our Goals
©2011

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