Erik Torstensson and Natalie Massenet didn’t just tell their love story. They branded it.

She was the superstar founder of luxury shopping site Net-a-Porter turned venture capitalist. He was a Swedish creative director who worked with the industry’s biggest names and co-founded a denim brand favored by supermodels.

Together, as fashion’s golden couple, they flew private and partied with people like Dasha Zhukova and Victoria Beckham. Ms. Massenet wore Valentino, Chanel and Oscar de la Renta; Mr. Torstensson was rarely without his Patek Philippe.

At galas and in interviews, they touted their love for each other’s style and minds, and extolled the way their personal and professional lives were intertwined, though they never married.

Speaking with The New York Times in 2023, Mr. Torstensson hailed Ms. Massenet as “the queen of everything,” describing her as “the smartest person in the world. And the kindest.”

“She literally doesn’t have a bad word to say about anyone,” he added.

That was before this summer, when he sent his friend Marcus Dunberg, a Swedish novelist and consultant, a text message that ended: “She’s going to war.”

On Aug. 20, their expertly curated life exploded in spectacular fashion when Ms. Massenet, 60, filed a lawsuit against Mr. Torstensson, 46, in California Superior Court in Los Angeles.