YOU CAN'T SAY ROSEANNE DOESN'T learn from her mistakes. Married to third husband Ben Thomas on Feb. 14, 1995, she never, to the best of anyone's knowledge, had his name engraved on her backside (her "Property of Tom Arnold" tattoo was reportedly covered up after she and her second husband split in '94). And before she wed Thomas, her onetime chauffeur and bodyguard, she made sure her fortune—a chunk of which had gone to Arnold and to first husband Bill Pentland—wasn't part of the deal. "Honey," she told The Advocate magazine at the time, "there'll, be prenuptial agreements up the ying-yang from henceforth."

They'll come in handy, because the ex-sitcom queen, 45, and Thomas, 31, have separated. At about 4 a.m. on New Year's Day, Ben went to their Encino, Calif., home, argued with his wife and broke a window before a judge issued an emergency protective order. "He was boisterous and using abusive language," says LAPD Lt. Anthony Alba. On Jan. 8, Roseanne filed for divorce, asking that her millions be considered separate from Ben's assets and that she get sole custody of their son Buck, 2.

Exactly what caused the breakup is unclear. Roseanne, who once called high school dropout Ben "perfect for me" in a PEOPLE interview, "is sorry it didn't work out," says her manager Jeff Wald. "She holds Ben in highest regard." Others do not. "After marrying her, Ben's head swelled so much I'm surprised he didn't float away," says his stepbrother John Williams, who once worked as the pair's driver. Adds a friend of the couple: "Ben suddenly had access to money, and he wanted to control it."

For now, Thomas is believed to be living at the couple's Lake Arrowhead spread, but since he signed a prenup, his digs are sure to get humbler. Roseanne, whose new syndicated talk show premieres this fall, remains at the rented Encino mansion, where, if first husband Pentland, a guest at her third wedding, gets his wish, she'll spend some time alone with Buck. "Roseanne has never been without a man," he says. "I hope she'll give singlehood a shot and get to know the great person she is."

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