The America's Got Talent host has confirmed he and the singer - who have four-year-old twins Moroccan and Monroe together - have been living apart "for a few months" and friends blame his heavy work load for the separation.

A source told E! News: "She is heartbroken. This has been going on for months. It has a lot to do with Nick's career choices. He does not have to work, but he's been throwing himself into gigs and projects. She has tried and tried to get him to stay home more, but he always uses work as an excuse. When she points out that, financially, he does not need to be working as much as he does, it p****s him off and pushes him farther away. He hates when people assume he's living off her money."

According to TMZ, "Nick is incredulous Mariah is bitching about his work ethic ... he says he's generated $75 million since 2011 for the family." Yeah, but her point is that he doesn't need to because she's probably the wealthiest singer in the world. And therein lies their issue. Not only is he 11 years her junior he also earns less money. It's time for Nick to find himself a 22-year-old waitress who shows a lot of promise.

If they do make the split permanent, 44-year-old Mariah is expected to base herself in New York, while Nick wants to be in Los Angeles, meaning they could face a tussle over the care of their children.

"She wants to be in NYC full-time, but he's been wanting to spend more and more time in L.A. If and when they split [for good], she intends to stay in NYC with the kids. She will fight for the kids. She is totally focused on them."

Nick recently vowed his 'main focus' was on the twins when he confirmed he and Mariah had been having problem, saying: "There is trouble in paradise. We have been living in separate houses for a few months. My main focus is my kids."

Now to the Kimmy involvement... TMZ's multitude of sources say: "Nick's appearance on Big Boy's radio show in March was the beginning of the end. Nick played Big Boy's game - name the 5 celebs you've slept with. Nick named 5, but our sources say the one that made Mariah insane was Kim Kardashian (video here - it's of the interview, not another Kardashian sex tape). We're told Mariah tore into Nick for weeks... feeling humiliated and the relationship never recovered. We're told it went from bad to worse when Nick went on Howard Stern and talked about Mariah not giving it up before they got hitched. She went nuclear."