One reason for the decline in marriage is the rise of cohabitation. The number of Americans cohabitating with their romantic partner has more than doubled over the past three decades. A recent survey found that men in cohabiting relationships are just as satisfied in their relationships as married men—but women in cohabiting relationships are 13 percentage points less likely to say they are satisfied compared with married women.

Here’s another example: today, a record 44 percent of women under 30 consider themselves to be liberal, compared with only 25 percent of men in the same age category. But evidence suggests that both liberal men and women are less interested in committed relationships than their conservative counterparts. For instance, a survey from the Institute for Family Studies found that 58 percent of unmarried Republicans are interested in marriage, compared with only 47 percent of unmarried Democrats.

This gap is exacerbated by the fact that as women become more successful, their standards for an acceptable romantic partner tend to increase.

Relative to men, a larger percentage of women say that “not being able to find someone who meets their expectations” is a major reason they are single. If you’re a woman, and you decide to rule out everyone who is right of center, and you want someone with a commensurate degree (young men continue to drop out of education and the workforce), then your dating pool will be very small indeed.

[There’s an interesting scene in “Up in the Air” that addresses this trend. The character played by Anna Kendrick lists off a long set of prerequisites for ‘the one’ to George Clooney and Vera Farmiga, and then says anything less is “settling, by definition.” They respond — ironically, in the context of the film — that “settling” really means just adjusting expectations to reality. Dating is a miserable enough experience for most people anyway, so prolonging it over unrealistic expectations or some form of FOMO is going to make people more unhappy than less so. Marriage and commitment are the keys to happiness, as long as people understand that both take a lot of work and that they’re not the center of the universe. — Ed]