The publication reported that while it was not yet clear what caused the split between the Vogue chief and the telecom millionaire, the relationship appeared to have been cooling off for a while.
In November, Page Six reported that the marriage had gradually been unraveling since 2013, when it emerged that Bryan owed the IRS approximately $1.2 million in back taxes.
"That was the beginning of the end," a source told the publication at the time. "He started to become a liability. It's been quite a while since they've been seen together."
The report on Wednesday claimed the pair are now "done for good" and pointed to speculation that Bryan had returned to his ex-wife Katherine Bryan — the woman he left when he began a relationship with Wintour in 1999.
However, a source told the publication that there is no truth to this gossip.
"Katherine and Shelby have kids together [and] are friends. That's all," they commented.
As The Daily Mail underlined, the pair's rumored separation could lead to a multimillion dollar divorce, with Wintour estimated to be worth $35 million, alongside her husband's own sizable fortune.
The newspaper noted that Wintour and Bryan's pairing in 1999 caused a stir as the investor was thought to have walked out on his wife to be with the media mogul. At the time, Wintour had just gone through a divorce from her psychiatrist husband David Shaffer. The happy couple then tied the knot in a top secret ceremony in 2004.
According to the outlet, Wintour has been known to socialize with a wide circle of male pals, including British actor Bill Nighy, with whom she enjoyed a dinner in February. However, when asked about rumors of romance between Wintour and himself back in 2015, Nighy was quick to quash any speculation.
"I obviously have nothing to say about that. There are a lot of rumors about me and probably about Anna Wintour," he said.
The rumors of a separation come amid a turbulent year for Wintour, as the newspaper underscored. In May, fashion journalist André Leon Talley — who was once a close friend and confidante of the fashion maven — released his memoir The Chiffon Trenches, in which he painted a scathing portrait of his former pal. The next month, Vogue's publisher Condé Nast was accused of widespread racism amid the ongoing Black Lives Matter movement. In response to the allegations, Wintour publicly apologized for race-related "mistakes."