Two introverts could make each other miserable. Two S&M devotees could be unhappy together. What does this do to the idea that it's best to find a mate just like you?

Well, Israeli psychologists studied 248 married couples and found that “as hypothesized, greater similarity between partners was associated with higher levels of marital satisfaction.”

Hmmm…

In other research, UCLA psychologists studied 180 couples, some “distressed” and others not, and found that having similar personalities “did not independently predict relationship satisfaction.” The researchers speculated that “similarity between partners’ personalities may not be closely tied to marital happiness.”

Yet another study from eHarmony.com, a popular dating site, found that “similarity and convergence in personality may benefit relationships by promoting similarity and convergence in partners’ shared emotional experiences.”

Interestingly, religiosity did not seem very important in most reports. Similar attitudes about religion and politics turn out not to be very good predictors of relationship happiness, which may help explain why Mary Matalin and James Carville have managed to stay married through both Clinton and Bush years.

Really all about you?
At least one study has suggested that it’s not so much the other person’s personality as it is yours. Happy people tend to be happy in relationships. The lovers and spouses of people who are less negative in their outlook and behavior tend to be more satisfied, too.

Where does this leave us? Without a magic formula. It seems safe to say that strong attraction may flutter the sheets but it is no guarantee of happiness (if we’re talking happiness that lasts longer than an episode of “Chuck”).

It also seems safe to say that the person with whom you had so much fun deconstructing "Teen Titans" could be terrible in bed and make you equally unhappy in the long run. The man you thought was a nerdy loser could turn out to be Tarzan in bed and your ideal husband.

This is why they write poetry.

But don’t let all this uncertainty stymie you. Take a risk and get out there and make 2008 THE year!

Oh, and one more thing before you go: If that new person you are ga-ga over smells anything like your mom or dad, you might want to compare family trees.

MSNBC.com columnist and Glamour magazine contributing editor Brian Alexander’s book “America Unzipped: In Search of Sex and Satisfaction" will be published Jan. 15 by Crown/Harmony Books.

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