Muscle-bound gym magnate David Barton has split with his wife of 15 years, Susanne Bartsch. The beefy 44-year-old boss of David Barton gyms and 1980s nightlife doyenne Bartsch, 59, decided to call it quits after an extended rocky period. A source told us, "They've been on and off for a while. He moved out of their home a while ago, but recently the separation has become more definitive. They have not filed for divorce, and while they remain friends, it is over." The two married in 1995 in a Playboy-sponsored ceremony, with Betsey Johnson and Ingrid Sischy among the 43 bridesmaids. The couple have a son, Bailey, 16. They briefly split in 1999 but soon reconciled. Friends of Barton, who has six gyms in the US including three in New York, deny rumors that he has a new love interest but admit "he is dating." Barton confirmed the split and said, "Susanne is one of the most amazing women I've ever known. I know we will be friends forever."