The marriage of pop singer Pink and her husband of two years, motocross racer and former The Surreal Life star Carey Hart, has ended, the singer's publicist, Michele Schweitzer, tells PEOPLE.

"Pink and Carey Hart have separated. This decision was made by best friends with a huge amount of love and respect for one another," says Schweitzer, adding, "While the marriage is over, their friendship has never been stronger."

Pink, 28, and Hart, 32, met at the 2001 X Games and broke up for a time in 2003, but the split was well behind them in 2005, when the singer popped the question to her beau as he sped around the track during a competition in Mammoth Lakes, Calif.

They married in January 2006 at a non-denominational ceremony in Costa Rica.

What happened? Rumors of cheating have been rampant for quite a while and here's Carey Hart at the Tabu Ultra Lounge at the MGM hotel and casino in Las Vegas, Nevada, earlier this month (Feb 11). Motocross star Hart, 32, was with a posse of pals - while Pink was not there, club sources said. He posed for a photo with one host at the club.

No wonder.

Back in September she was already telling friends things weren't working out.

Pink Makes Out with a Girl
Pink Gives Hubby Lapdance
Pink to Divorce Husband?
Pink's Hubby a Cheating Hart