Greek Tragedy: Mariah Carey and Fiance's Relationship Crumbled During Greece Vacation, Reports Say

The end came for Mariah Carey and her billionaire fiancé, James Packer, after a nasty fight aboard his yacht in Greece last month, according to reports.

Read: Mariah Carey's Wedding to Billionaire Reportedly Called Off Over Her 'Extravagant Spending'

The couple were vacationing on Packer's yacht when he allegedly did "something really bad” to the singer’s assistant, according to a report.

A source told People magazine: "James has not been in a mentally healthy place. His behavior is not a desirable situation for Mariah so she unfortunately had to leave him."

Packer has a history of getting into bizarre scraps. Two years ago, the casino tycoon and fellow Australian mogul David Gyngell got into a street brawl in a dispute over supermodel Miranda Kerr.

A rep for Packer calls the reports of bad behavior "simply untrue."

Others contend that the problem is not with Packer at all, but with Carey.

A source told People magazine: "They split because [Mariah] has issues. James is definitely an oddball, but a brilliant, great guy."

One of those issues is said to be the “Heartbreaker” singer’s “extravagant spending.”

Another issue was that Packer allegedly believed Carey was getting a little too cozy with backup dancer Brian Tanaka, according to reports. 

Packer's rep said: "They definitely won't be getting back together now."

Read: Why Amber Heard Donated $7 Million Divorce Settlement From Johnny Depp

But Carey was spotted still wearing her 35-carat, $7.5 million engagement ring in Malibu Thursday night.

Watch: Jon Voight Speaks Out on Daughter Angelina Jolie's Divorce From Brad Pitt