IVASHstudio / Shutterstock

Every weekday at 7:40 a.m., the hosts of a program called The Anna & Raven Show give early-rising commuters in Connecticut and New York the opportunity to weigh in on a local couple’s dispute in a recurring segment called “Couple’s Court.” “Couple’s Court” is precisely the kind of thing that’s irresistible to the hopelessly nosy—and a few weeks ago, on a Monday morning, an engaged couple named Adam and Kat phoned into the show with a dilemma that’s become familiar to many in recent years. Adam, who counts a woman he’s known for years among his best friends, had recently asked Kat to invite his female friend to be a bridesmaid in their wedding.

Kat, who wasn’t close with this friend of Adam’s and had planned to include only her family members and best friend in her side of the bridal party, was reluctant. She encouraged Adam to invite the friend to join his own half of the wedding party, including her among the groomsmen. The problem was, he was equally reluctant. “Traditionally, people don’t do that,” Adam said on the show, and he noted that adding a woman into the mix on his side would complicate other, traditionally guy-specific activities such as the bachelor party. Still, he said of his female friend, “She’s way too close to me for her to just be sitting [with the other guests] at the wedding.”

The two hosts (and many callers) sided with Kat, encouraging Adam to include his friend as a “groomsmaid.” (“I think your answer’s a little outdated,” one of the show’s hosts said to Adam.) But as close platonic friendships between men and women seem to have become more common in the past few decades, so has the dilemma of how exactly to honor a friend or family member of a different gender within the context of a wedding party. Engaged brides and grooms seek advice about whether it’s acceptable for a bride to include her male best friend among her bridesmaids or for a groom to invite close female friends to his bachelor party. Women post on social media about feeling left out because their male best friends have excluded them from their wedding party on the grounds of gender. And yet, according to new data provided by the wedding-planning website The Knot, fewer than four out of every 10 marrying couples in 2019 had mixed-gender wedding parties. That figure exposes an unfortunate incongruity between custom and reality: In a time when mixed-gender friendships are believed to be thriving, many wedding parties remain divided by gender in the name of tradition.

Lots of wedding traditions are packaged and sold to brides—and grooms, but, realistically, mostly to brides—as ancient rites of passage, when really they’ve existed for less than 200 years. (See: diamond engagement rings, introduced by an ad campaign in the early 20th century, and white gowns, popularized by Queen Victoria in 1840.) But wedding attendants in single-sex groups actually do seem to date back to antiquity. At least one of the tradition’s competing origin stories dates all the way back to biblical times: At the wedding of Jacob to Leah and Rachel, so the story goes, each bride brought her own maid. Meanwhile, in ancient Rome, marriages needed at least 10 witnesses, which meant the bride and groom would each arrive with a small posse in tow.

Most of these origin stories, however, come from times in history when women and men were not usually assumed to have meaningful platonic friendships. Last year, Rebecca Adams, a sociology professor at the University of North Carolina at Greensboro, told me when I spoke to her for a story about exes who stay friends after breaking up that for much of modern history, men and women simply weren’t assumed to have much in common. Generally speaking, women’s roles were at home tending the house and children and men’s roles were outside the home in civic society, so the social lives of men and women took place in radically different spheres. But when women began to pursue higher education and work alongside men in the mid-20th century, things changed: Men and women had common experiences to bond over or commiserate about, and, in short order, they began to enjoy platonic friendships.

Little hard data exist on how many close friendships are between adults of different genders, but Adams and other researchers believe that in the past few generations, men and women have enjoyed more close friendships, with less outside suspicion. In 2014, for instance, the then-director of Stony Brook University’s Center for the Study of Men and Masculinities, Michael Kimmel, said he’d been asking his students for 25 years whether they had a good friend of the opposite sex. At first only about 10 percent said yes, but by the mid-2010s, almost everyone did. Similarly, Judith Kegan Gardiner, a friendship researcher and professor emerita at the University of Illinois at Chicago, wrote to me in an email that “from what I can see (principally of white, middle-class people), adult cross-sex friendships are growing more common and becoming more casually accepted, [and] attract less suspicion of inevitably sexual behavior.”

Miriam Kirmayer, a clinical psychologist and friendship researcher based in Montreal, often works with young adults, and she told me that their cross-gender friendships come up regularly. Given the life stage young adults are in, their uncertainties about how to honor adult friendships and close family relationships in wedding contexts without excluding anyone or hurting feelings also come up. Kirmayer isn’t surprised to see that the clash between the old tradition of gender-segregated wedding parties and the new ubiquity of mixed-gender friendships is creating stressful situations.

Asking someone to stand up with you on the day you get married, Kirmayer says, is one of the few codified ways to publicly commemorate or honor close adult friendships. But because the number of spots in a wedding party is often limited to just a handful, choosing to include one friend often means choosing to exclude another. Single-sex wedding parties can already cause hurt feelings, “and because having mixed-gender bridal parties perhaps isn’t as common, that would create even more room for conflict,” Kirmayer told me. She understands why some couples might hesitate to deviate from the norm. “It could be seen as choosing somebody else over the person that you were, you know, ‘supposed’ to.” (The old, crude adages about where exactly on the loyalty list your “chicks” or your “bros” belong would seem to apply here.)

That said, prioritizing the tradition of single-sex wedding parties over just asking your closest friends or family members to be wedding attendants can be equally hurtful, especially to those who find themselves without a role in the wedding because of their gender. Situations like Kat and Adam’s, according to Kirmayer, raise the question of whether the exclusion of a dear friend from a wedding party in the name of tradition comes from a place of anxiety or fear. In those cases, she told me, she would advise the bride or groom to consider what they’re worried about, and what the worst that could happen might be.

“Sometimes identifying the worst-case scenario is helpful because when we say it out loud, we realize, ‘Okay, this maybe isn’t as likely as we’re assuming,’” she said. “And it also allows us the opportunity to ask ourselves, if somebody is disappointed, if somebody is upset, or if we feel judged in some way, how we would cope.”

Disapproval from onlookers is certainly a realistic possibility; weddings are, after all, often places where several generations and their individual social norms converge. But weddings have also come to be recognized as statements about a couple’s unique personality and value system: For the same reason that some couples have begun to opt for mixed-gender wedding parties, others have opted to, for example, have their wedding festivities in an ever-expanding variety of venues, venturing away from the traditional church ceremony and hotel reception. The selection of the particular friends and relatives who stand up with a couple on their wedding day can provide a way for the couple to express their own distinctive values—and to take a moment on the day that celebrates their relationship to honor the other relationships that complement and support it. The genders of those friends and family members should take a backseat.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.