Nick Cannon Has Filed for Divorce from Mariah Carey

Cannon filed divorce papers on Dec. 12, according to TMZ, which first reported the story Friday, noting that Carey had been working on a property settlement for the couple in advance of her husband making the first step in court.

The singer and the America's Got Talent host were both spotted without their wedding rings in August, and a source told PEOPLE the pair had been living apart for months.

Carey, in the midst of their split, has been focusing on her career, inking anartist-in-residence deal in Las Vegas where she is set to perform an 18-song set list of all her No. 1 hits at The Colosseum at Caesars Palace.

During the separation, Carey remained at their Manhattan apartment with the couple's twins, Moroccan and Monroe, who turn 4 in April, while Cannon "has been staying in hotels," the source said.

The separation was contentious, and Carey was reportedly three-hours late for a December taping of a Rockefeller Center Christmas tree special because she was engaged in a five-hour call with attorneys over not only property but the couple's children, a source told PEOPLE.

Cannon said the couple was trying to remain amicable and focus on their children over the holidays.

Sources said Carey's professional life may have contributed to their split, even as Cannon took to Twitter in September to assert, "I love Mariah Carey and that will never change!!!!" In a series of 20 posts, he also defended her as a strong mother.

"When things don't go well career-wise, sometimes you turn on your other half," the source said, referring to the sluggish sales of Carey's most recent album, Me. I Am Mariah … The Elusive Chanteuse, released in May.

The couple surprised fans with a secret wedding in the Bahamas in 2008, after a six-week courtship. In May 2013, for their fifth anniversary, they renewed their vows at Disneyland.

Carey's rep is not commenting on her personal life while Cannon's rep did not reply to PEOPLE's requests for comment.