The rumors about Mariah Carey’s marriage to Nick Cannon  just keep getting worse. The pair allegedly did not even celebrate their sixth wedding anniversary last week, and are barely in contact.

So why have they not divorced yet? According to OK! Magazine, it is because of money. "Mariah'd cut him loose right now. But she's worried about him making a grab for a huge chunk of her $515 million fortune," a source says.

Carey and Cannon began dating in 2008 before making their relationship public. They wed within two months of their first date, and renew their vows every year. They now have twins, Monroe and Moroccan. Cannon is said to be shocked about Carey wanting to end their marriage.

"Nick feels burned that Mariah is ready to pull the plug. They have a pre-nup, but after Nick tells his side of the story Mariah will most likely settle with him financially and realize her once beautiful marriage has evaporated."

But the relationship is said to have gone downhill due to cheating rumors. According to OK! Magazine, Carey, 43, has been getting into “massive fights over Nick’s sex romps with other women” and is devastated.  Carey is believed to be concerned about Cannon’s wandering eye, especially since his MTV show “Wild 'N Out” is staffed with gorgeous women. At the same time, the National Enquirer claimed earlier this year that Carey was getting a little too close for comfort to young men in the music industry.

Meanwhile, the troubled pair recently placed their 11,750-square-foot Bel Air mansion on the market for $12.9 million. That's $5 million more than what they paid for it in 2009.