Roseanne Barr's private life has been all over the tabloids lately and now her boyfriend is talking, too, saying that he and the TV star may marry after she divorces Bill Pentland. Tom Arnold, 30, a comedian who was Barr's opening act in her stand-up days and now a writer for her show, told USA Today, "Marriage has been discussed . . . It would be after the divorce. That's the most important thing." Arnold describes Barr, 36, as "the strongest woman I've ever known" and resents those who portray their relationship as an affair. "I'm from Iowa, see, and (the relationship is) just not a sleazy thing," he says. "It's sad that she's getting a divorce but if she's not happy . . ." Arnold also said Barr met during the Memorial Day weekend in Los Angeles with Brandi Brown of Dallas, the daughter she gave up for adoption 18 years ago.