It takes a lot to shock the fashion world, but the breakup of the power couple behind Zadig & Voltaire managed to do it. The global French brand, known for the edgy clothes and accessories carried at more than 300 directly owned boutiques around the world, is run by C.E.O. and founder Thierry Gillier and artistic director Cecilia Bönström, whom he hired as an assistant in 2003 and reportedly wed in 2016. But now that Gillier is allegedly coupled with Cecilia’s twin sister, Charlotte, things are a little compliqué. (Charlotte could not be reached for comment.)

After two decades of marriage, Charlotte Bönström is in the process of divorcing her husband, Vittorio Assaf, the New York restaurateur who owns the chain of Serafina restaurants with his partner, Fabio Granato. Assaf has denied reports that he and Cecilia have coupled up. “It is very difficult,” Assaf told the New York Post’s “Page Six.” “But I have nothing to do with the sister of Charlotte.” How did these two charmed couples go so awry?

Cecilia and Charlotte in 2013.

The Bönström sisters, both 50, were born in Gothenburg, Sweden, and pursued modeling as young women. Cecilia, who moved to Paris and signed with Elite, was very successful. She worked steadily, but at age 33 she decided to pivot to the design side of the fashion business. “And I said to myself, I want to work for Zadig and Voltaire,” she told Into the Gloss. “Don’t ask me why—destiny, I guess?” In 2006, after three years as an assistant there, she was named artistic director.

In the intervening years, as the brand evolved under Bönström’s creative leadership, Zadig & Voltaire’s fortunes grew. The company bet big on the United States, opening New York flagships on Broome Street and Madison Avenue. In 2018, Cecilia was given the Fashion Innovator Award at The Daily Front Row’s Fashion Media Awards; Paris Jackson presented the honor to her in a crowd that included Gigi Hadid, Nicki Minaj, Martha Stewart, and Irina Shayk. Recently, Cecilia has been rethinking the brand’s environmental impact and developing new production practices alongside a chief sustainability officer.

Zadig & Voltaire’s success was a boon for Bönström and Gillier’s personal fortunes as well. According to WWD, Gillier’s net worth is estimated at $514.8 million; in addition to his earnings from Zadig & Voltaire, he comes from a wealthy textile family in Troyes, in northern France. (His grandfather was a co-founder of Lacoste.) The couple, who have three children from previous relationships, also have a son together. He is now nine years old.

How did these two charmed couples go so awry?

It is not confirmed if Gillier and Bönström have officially tied the knot, which could have large financial implications in terms of their separation. Who gets the real estate? The couple has a restored farmhouse in Normandy, and in 2017 Gillier bought a magnificent apartment on Rue Galilée, just south of the Avenue des Champs-Élysées, with views of the Eiffel Tower. According to W magazine, which featured the home and its “rapidly expanding” art collection, with works by Picasso and Basquiat, Gillier reimagined the space with the help of starchitect Christian Liaigre. “Thierry is always looking for new homes,” Cecilia told W. “He’s the same with everything he does: always looking for the next thing.” Which is putting it mildly, given recent events.

Jilted husband and co-owner of the Serafina restaurants, Vittorio Assaf.

Meanwhile, Charlotte has spent the past 20 years living in New York and married to Assaf, with whom she has two children. Although Charlotte and Vittorio maintained an apartment in Manhattan and a home in the Hamptons, their fortunes were considerably smaller. Like most restaurants, Serafina’s business suffered due to the pandemic—a GoFundMe account was started to support the restaurant staff.

Until recently, the sisters were close friends and collaborators. In 2019, to toast Zadig & Voltaire’s boutique in East Hampton, Charlotte organized an opening party and dinner for Cecilia at—where else?—Serafina.

Yes, they can. Especially twin sisters.

It seems that Cecilia first discovered the affair between Charlotte and Gillier in the earliest days of the pandemic, as she began posting quasi-cryptic messages on Instagram about a lack of integrity, tagging her sister and husband. On March 15, a close-up of her red, watery eyes was accompanied by the hashtags #momentoftruth, #iknowwhoiam, and #nolies. A New York fashion editor heard a rumor that Cecilia had discovered Charlotte and Gillier in bed together. But a source close to the brand says, “He didn’t go very far—he’s clearly still in love with his wife, and [Charlotte] is the next best thing. It’s almost sweet in how lazy it is.”

Although Cecilia’s personal life is messy, her professional one continues apace. “She’s very much staying at Zadig & Voltaire,” says the source close to the brand. “She’s the first one [at the studio] in the morning, and the last one to leave. You’ve never seen anyone work so hard.”

Ashley Baker is the Style Editor for Air Mail