The singer-actress split from Welsh TV presenter Matt Johnson earlier this year and has since moved on with the British hunk, who she has been dating for a month, reported Daily Star.
Gandy is said to have introduced Barks as "my girlfriend" at a yacht party in Monaco last month.
"They can't keep their hands off one another. They kept it quiet at first but now they're happy to publicly display affection," a source said.
Gandy previously dated The Saturdays pop star Mollie King.