People like to say that American culture has a puritanical streak: one that entails, among other things, a certain haughty piousness, instilled by the killjoys who reached New England’s shores in the 17th century. Yet the Pew Research Center, in a pair of reports released last month, asked participants in various countries about a host of moral issues—and found few in the United States that were widely condemned. Spanking children?

Doctor-assisted euthanasia? Clear majorities said they weren’t morally wrong. Gambling? Marijuana use?

Compared with respondents in many nations, Americans were notably permissive. The poll also revealed clear political divides: Republicans were much more likely to oppose homosexuality and divorce, for instance, and Democrats were more likely to reject the death penalty and extreme wealth.Only one behavior, in fact, received near-unanimous disapproval: infidelity. Ninety percent of Americans said that a married person having an affair is morally wrong, and their position didn’t differ dramatically based on political party, age, or gender.

Compare that to Germany and France, where participants were roughly split down the middle.The Pew poll is one of many suggesting that when it comes to monogamous commitment, Americans aren’t messing around. Well—technically they are: Studies indicate that a third to half of people in the U.S. have been sexually unfaithful, according to the evolutionary biologist Justin Garcia’s new book, The Intimate Animal. If you were to include “emotional infidelity” or kissing, which apparently some people don’t think is cheating, the numbers would rise.

But that hasn’t stopped Americans from judging cheaters, even as attitudes toward other sexual behavior—premarital sex, casual sex, the use of contraception—have loosened.[Read: The basic drive that humans might be losing]No one wants to be deceived. Yet disdain for cheating seems to derive less from a simple desire for honesty and more from a commitment to the couple as an exclusive unit. Consensual nonmonogamy is widely stigmatized; one 2021 study found that of participants who weren’t personally interested in engaging in polyamory—meaning multiple romantic relationships—only 14 percent said that they respect people who do practice it.

And of course, there are many ways to betray a partner that have nothing to do with sex—and that many people seem more willing to forgive. For a qualitative study, Jenny van Hooff, a sociologist at Manchester Metropolitan University, interviewed a woman whose partner had racked up a massive amount of debt without her knowledge; collectors came and stripped the house of her belongings, and she herself had to pay back what was owed. “But it’s so much better,” she told van Hooff, “than if he cheated on me.”Monogamy, it seems, is one of the few moral rules that Americans feel they can grasp onto, in an age when many no longer look to religion or a unified culture for social norms.

It serves many people well: Committing to one partner, growing together through change, and staying loyal even when it’s difficult can grant them profound purpose. Yet other sources of meaning and community exist, too—and other ethical obligations. The intensity of the American allegiance to monogamy might reveal something about national priorities: a sense of duty to ourselves, our partners, and our household—perhaps more than to anything or anyone outside of it.Amy C.

Moors, a psychologist at Chapman University, likes to play a game with her students. She tells them that in the United States, people who get married can receive a certain number of federal benefits. She names some examples: joint income-tax filing, medical decision-making authority, the ability to sponsor someone for immigration.

Then she asks how many laws they reckon consider marital status in determining who’s eligible. No one has ever guessed more than 100.The answer is more than 1,000. Some of these laws are enormously consequential: They could grant someone housing assistance, or custodial rights, or bereavement leave after a partner dies.

Others are niche: One concerns who can inherit land on Lake Michigan’s Sleeping Dunes National Lakeshore, now that it has become a national park. But Moors’s point is that compared with other countries, the U.S. offers an especially robust package of spousal perks.Americans are motivated to think of marriage, in other words, as the key to a stable and virtuous life. Fewer have actually been getting hitched, but that might be a testament to how seriously the institution is taken; people tend now to think of matrimony as something for which they need to prepare—save up money, get their career in order, find their soulmate. And monogamy is commonly associated with all kinds of positive traits: It receives what psychologists call a “halo effect.” In one study, when Moors and her colleagues described fictional characters as monogamously coupled, participants were more likely to see those characters