T

he trends in marriage and mating in recent years have been surprisingly positive. Who could have imagined a couple of decades ago that we would be seeing declining rates of divorce, lower rates of teen pregnancy, and higher rates of marital fidelity? Unfortunately, all of these trends—which stem in part from a greater willingness to delay romantic commitment—have had unintended consequences as well. The flip side has been lower rates of marriage, higher rates of cohabitation, and lower rates of fertility.

To understand which groups have benefited from this new landscape and which have suffered, we can turn to Mark Regnerus and his new book, Cheap Sex. A sociologist at the University of Texas at Austin, Regnerus has made a career out of explaining the mating habits of Americans. He has been accused of trying to advance a political agenda through his research on the children of same-sex parents. He was even threatened with dismissal for it, his tenure notwithstanding. That witch hunt failed, and one would be hard-pressed to find a single assertion in his new book that is not backed up by significant data.

Regnerus takes great pains to explain just how revolutionary reliable contraception has been to human behavior. Before the invention of the Pill, when sex necessarily involved the risk of pregnancy, “the mating market . . . was populated by roughly equal numbers of men and women, whose bargaining positions—averaged together—were roughly comparable and predictable, with men valuing attractiveness more than women, and women valuing productivity and economic promise more than men.”

But now that sex is as much for fun as procreation, “we have a split mating market, one corner of which is for people primarily looking and hoping for sex with no strings attached and the other corner of which are people interested in making the strongest of commitments (marriage), with a rather large territory in between comprised of significant relationships of varying commitment and duration.” Women are concentrated more in one corner of the market and men in the other. Hence, the increasingly common perception of a so-called man shortage.

Regnerus pauses at many points in the book to assure readers that it is neither sexist nor ignorant to describe such a market, nor to point out that there are innate differences between men and women. As Regnerus notes, “critics tend to only speak of the sexual exchange model by disparaging it and asserting that it is archaic—on ‘the wrong side of history,’ patriarchal, and ignores love in its many modern expressions.” But that doesn’t change the facts on the ground. On average, women and men view sex differently. “Across multiple studies,” he notes dryly, “women were found more likely to have regretted casual sexual interactions, while men’s regrets were more often about missed sexual opportunities.”

“Cheap sex”—what Regnerus calls access to sexual pleasure with little effort or commitment—has done much more than make it difficult for single women to find husbands. It has increased cohabitation. It has affected the frequency with which married people have sex. It has changed homosexual relationships. It has altered family structures, changed people’s political views and religious practices. And according to Regnerus, these revolutionary trends show no signs of slowing.

The easiest way to measure how “expensive” sex is in terms of the resources required to procure it is to see how long people wait to have sex. Looking at data from a 2014 survey called “Relationships in America,” in which 15,000 Americans between the ages of 18 and 60 were interviewed, Regnerus concludes that “sex before a relationship begins is now the most common experience.” Most relationships were consummated within two to three weeks.

Surprisingly, there is not a great deal of difference between how men and women view the matter. One might speculate that men would want to brag about how quickly they bedded a woman. But women seem almost as inclined to move to the next level as quickly as men do.

Some of the women that Regnerus and his colleagues interviewed for the book told him that they wished they had waited longer—particularly in cases where they genuinely liked the man involved and thought there might be the possibility of a longer-term relationship. Sarah, a 32-year-old woman from Austin, explains that with each of the men she dates, “I’m always like ‘Ok, cool, I’m going to (wait) this time,’ and then I meet the guy and there’s chemistry and the next thing I know I’m sleeping with them and I’m like, ‘S–t.’”

Reasonably enough, Regnerus wants to know “why women demand so little of men in return for offering men what they want.” It’s not simply the case that Sarah knows these men can go elsewhere to find faster women if she keeps them tapping their toes too long (he refers to this problem as the collapse of the women’s “cartel”). It’s also because “many [women] do not need what men can offer.”

In another interview, a woman living with her unemployed boyfriend (whom she won’t marry until he gets a job) describes how when “he kicks the couch, [it] is our signal to go upstairs and do it.” It’s hard to imagine sex getting cheaper than that.

Before the sexual revolution, women actually needed men’s resources in order to settle down and have a family. This is the theme of recent books like Hanna Rosin’s The End of Men. Now many women have determined that men will simply be a drag on their own ambitions. With women getting college degrees at higher rates, men are often seen as inhibiting women’s economic progress.

Even women lower down on the socioeconomic ladder are not as interested in wedlock. Women who are on public assistance are less likely to wish they were married than those who are not. And only 36 percent of women who received four forms of public assistance wish they were married. “The more they need the help,” Regnerus writes, “the less confident they are that marriage will deliver it.”

Regnerus interviews more than one woman who says she wouldn’t want to marry her unemployed or underemployed cohabiting boyfriend. This does not seem to encourage the boyfriends to do more. “Men…work best under pressure,” writes Regnerus, “but social constraints upon what motivates men are rapidly disappearing today with little sign of a return.”

Still, from the data Regnerus presents, it appears that men are still settling down, but just waiting much longer to do so. This can create some worrisome side effects. Women are having fewer children, later in life, inviting more potential for complications. And more than half of births for women under 30 occur outside of marriage, making it more likely that children will grow up in homes that are less financially and emotionally stable.

The good news is that when men do marry, they generally seem to like it. It is women who initiate most divorces, and they are more likely to disagree with statements like “my relationship with my partner makes me happy” and “our relationship is strong.” Sometimes they disagree by as much as a 3-to-1 margin compared with men.

Even once they are married, women and men want different things. Regnerus notes that lesbian relationships actually have a greater risk of breaking up than heterosexual relationship in part because of women’s “high standards for relational satisfaction.”

Even if most of the men and women who want to marry are ultimately settling down, Regnerus argues that their longer period of time on the “market” can “yield unintended consequences of extending market mentalities—notions like cost-benefit estimates, risk assessments, and concern about settling—into the marriage itself.” These are not promising ways to think about our life partners.

Regnerus suggests that at a time when religious practice and belief are waning, people (especially women) expect a certain kind of transcendence from sex. He writes:

Great (infertile) sex is now a priority, a hallmark of the good life, signaling that our genital and psychosexual life—sexual expression and how we experience it—is close to the heart of being human…. Quality sexual experiences are increasingly perceived to be just as pivotal to human flourishing as clean air, potable water, edible food, ample shelter, and antibiotics.

But that is not what most men and women have gotten. Since the likelihood that women will achieve sexual pleasure is directly correlated with the amount of time they have been with a partner, this brave new world is not working out so well for them in explicitly physical terms, either.

Instead, both men and women are having sex like men—sex that need not be dependent on commitment, sex that need not involve any relationship at all. “But peel back the layers,” Regnerus writes, “and it becomes obvious that this transition is not a reflection of [women’s] power but of their subjugation to men’s interests.” All it takes is a kick of the couch.