The American Pie actress and Celebrity Big Brother star was spotted "looking intimate" with Fawaz Gruosi onboard a "massive yacht" at the Cannes Film Festival.
The rumoured couple - separated by 24 years - were seen mingling with the likes of Eva Longoria, P Diddy and Alec Baldwin at the Lady Joy Boat Party, according to The Hollywood Reporter.
Gruosi is the founder and president of luxury Swiss jeweller De Grisogono. The company had a revenue of €102.6m (£82.1m) in 2011.
Reid claimed to have married Zack Kehayov in August 2011, but later revealed that the marriage was not legal and went on a date with an unknown man the following December.
She was believed to be in a relationship with Danish businessman Michael Lilleund when she 'married' Kehayov and previously broke off engagements to talkshow host Carson Daly and German entrepreneur Michael Axtmann.