Avril Lavigne was reportedly seen flirting with another man in the lead up to her split from husband Deryck Whibley.
The Girlfriend singer - who announced she was separating from the Sum 41 rocker last week - spent a month partying on oil heir Brandon Davis's yacht in St. Tropez, South of France, and sources say the pair have grown very close.
One is quoted by gossip blogger Perez Hilton as saying: "She was downing shots, drinking booze from the bottle and play-fighting men on the beach.
"She wasn't acting like a married woman at all."
However, sources close to Avril insist she and Brandon are "not involved romantically" and are "just friends".
Last December, Deryck warned Brandon - who has also dated Lindsay Lohan and Paris Hilton - away from his wife after he discovered the pair had been for dinner together.
He texted Brandon, saying: "Stay away from my wife."
Even though their three-year marriage is over, Avril has vowed to stay friends with her estranged husband.
In a statement on her website, she said: "Deryck and I have been together for six-and-a-half years. We have been friends since I was 17, started dating when I was 19, and married when I was 21. I am grateful for our time together, and I am grateful and blessed for our remaining friendship.
"I admire Deryck and have a great amount of respect for him. He is the most amazing person I know, and I love him with all my heart. Deryck and I are separating and moving forward on a positive note."