Opposites Attract? Changes in Marriage Economics

While I initially took the course to fulfill my social science, my Economics 323: Gender Economics class has been distinctly interesting. Thinking about such qualitative social issues such as marriage and childbearing by attempting to grasp each concept with some sort of logical model has shifted my prospective and opened my eyes to a new way of thinking. One particular issue that we uncovered in class was the answer to the question: do opposites attract in marriage? We uncovered, using a gains from trade model, that opposites should—economically speaking—attract as there will be larger gains from trade when each individual in a couple specializes in the production of a good in which they have a comparative advantage. By the use of complete or partial specialization in the individuals allows the couple overall to reduce opportunity costs and maximize combined output.

This economic model is discussed in the John Shoven textbook Demography and the Economy. In chapter 3, Shoven summarizes Gary Becker's work Treatise on the Family:

Gary Becker's 1981 Treatise on the Family proposed an economic theory of families based on "production commentaries," in which husband and wife specialize in the market and domestic spheres, respectively, and hence, are more productive together than apart...By having one person specialize in domestic responsibilities, while the other supports the spouse and children financially, couples are more efficient than singles.

Becker's analysis aligns perfectly with the gains from trade theory and for a significant period of time founded the basis for much analysis within the marriage economics field. However, as our class discovered, this theory poses a problem when applied to modern data on marriage patterns. Research done on recent marriage patterns reveal that opposites may not actually attract and factors outside of production skills are increasingly relevant to the marriage decision. 

One particular factor, friendship, is discussed in the New York Times article Study Finds More Reasons to Get and Stay Married. The article discusses the impact on friendship between spouses on marriage utility:

One reason for [benefits of marriage persisting] might be the role of friendship within marriage. Those who consider their spouse or partner to be their best friend get about twice as much life satisfaction from marriage as others, the study found...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.

This seems to contradict what the initial gains from trade model that was proposed. Factors that would likely drive friendship in a relationship, namely similar education levels, similar interests, etc., are also those likely to reduce the comparative advantage between the individuals from a trade prospective. This research suggests there is a confounding factor other than these production factors that go into the overall utility (satisfaction) of marriage, and this factor is increasingly becoming more and more important.

But what caused the shift in the importance of the "friendship" factor. People across the United States did not just wake up one day and begin to increasingly think "gee, I should really marry someone that I am really friendly with".

The answer comes down to one word: cohabitation, or living with a "partner" without a formal marriage. According to the analysis of Neil Shah, writer for WSJ, on a Pew Research Center study:

For many Americans, staying single, cohabiting or raising children out of marriage increasingly looks like the best available option. Nearly 25% of young adults 25 to 34 who have never been married were cohabiting last year, up from under 22% in 2007, Pew says. Roughly 7% of adults 30 to 44 were cohabiting in 2010, too, according to a different analysis, up from 3% in 1995.

The increased importance of friendship within marriages flows directly from cohabitation. Individuals are taking longer to determine whether or not to marry another person, utilizing cohabitation to make this determination. These "couples", who often will not pool resources (specifically finances) and will not make the normal gains from trade decisions. As a result, they have had to look to other factors (similarity, friendship, etc.) to provide utility in a marriage.