Just in time for Valentine’s Day, those three little words everyone looks for in romance and marriage: portfolio diversification relationships.

“Forget about love,” says CMC’s newest economics professor Gregory Hess, somewhat tongue-in-cheek,, “you want to find a partner who helps you share economic risk.”

Hess, the Russell S. Bock Chair of Public Economics and Taxation, swears he started his research with a more sentimental approach. “I originally wrote my paper because I thought that initial love would be more important to a marriage, on average, in the long run. But what I found,” he says, “was the opposite.”

His paper, titled Marriage & Consumption Insurance: What’s Love Got to Do With It? is still under consideration at the University of Chicago’s Journal of Political Economy after a number of rounds of revisions. His study includes data from more than 1,300 marriages from 1979 to the present. He examined a variety of indicators, including socioeconomic backgrounds, health and fertility histories, labor market experiences, and income. “Perhaps we would all be better off if we could perfectly offset economic risks via financial markets so that marriages would all be about love,” he says, “but from what I’ve researched, initial love doesn’t last, and finding a good economic match can help couples weather more stresses and strains on their love.”

Like good financial portfolios, he says, the best marriages have negatively correlated incomes across different career paths---when one partner’s income is down, the other’s is on the rise. Just like diversification is good for our financial portfolios, it's also good for our marriages. Heeding the lessons of failed marriages of the likes of Tom and Nicole, and Charles and Diana, it’s best, he says, to marry from separate industries, and to spread the economic risk around.

Hess understands that the heart may not always follow the formula. If this month’s proliferation of hearts, roses, and engagement ring commercials leave you feeling breathless and blind to a partner’s balance sheet, Hess says, you’re not alone. “We all tend to underestimate the importance of economics in marriage decisions. Relying too much on initial love can lead you to choose a partner who is a bad economic choice, which too often leads to failed marriages.”

Hess articulates his formula at a dry-erase board in his office on a recent morning: Love + Economic Characteristics = Duration of Marriage.

This would be good news for someone who wanted to enter a marriage for financial comfort and security over love. It would conversely be bad news for someone who viewed love as more important in the marriage, but had married a bad economic match, when you’ve “substituted away” an important characteristic as a compromise to help reach the altar faster. After the honeymoon is over, financial strains on the marriage would potentially knock it off the altar, Hess says.

However (and this is where you may want to reach for an aspirin), the crux of his test is whether marriages that are good economic matches are indicators of longer marriages. For if love truly is the most important factor in the long run of the marriage for both people, then the couple has a chance of surviving the economic ups and downs because it outweighed the bad economic match. Hence, more love would suggest poorer economic matches, but longer marriages. Alternatively, if love is an unimportant factor in the long run, then people with more love would likely be worse economic matches, and they would have shorter marriages. In one case, good economic matches make marriages last longer. In the other case, it makes them last shorter. Empirically, Hess finds that good economic matches makes marriages last longer, which suggests that love just is not that important.

Of course, oversimplifying Hess’ model in this way does not individually address other variables that affect the duration of marriage, including race, religion, death of a loved one, individual values and morals, and family histories of divorce, though many of those attributes were identified in the national longitudinal studies he researched.

Hess says he knows his findings may sound pessimistic. And, yes, there are those cases where a perfect love match is also a perfect portfolio match, but, he says, don’t count on it. “We’d all prefer the best of both worlds, but there’s usually a trade-off. I’m hoping that love will someday outlast the economics,” he says, “but my research shows that we’re not there yet."

Apparently today's formula for love and marriage is a bit more complicated than one-plus-one equals two.