updated 10/11/2004 AT 01:00 AM EDT
•originally published 10/11/2004 AT 01:00 AM EDT
The source says the never-married Nixon, who now considers herself bisexual, embarked on the romance in January, six months after she amicably split from photographer Danny Mozes, 38, her companion of 15 years and father of her two children. The initial spark? A topic that would have had the Sex girls yawning over their brunch menus: public schools. For the past several years Nixon has lobbied for increased government aid to city schools—her daughter, Samantha, 7, attends one—and her girlfriend works for a nonprofit education-advocacy group. Although the woman has no children of her own, "they both share a passion" for that cause, says the friend.
The new companion prefers life outside the spotlight ("nothing public about this girl," says the friend). Yet Nixon, whom castmate Mario Cantone describes as a "grounded, no-nonsense woman," knew it was inevitable the romance would make headlines. (The couple aren't living together, but Nixon's daughter and 22-month-old son Charles "know her, and they have a good relationship," says the friend.) But she's unlikely to dish out any further details. "I understand the recent interest in my private life, and I appreciate how supportive everyone has been," Nixon tells PEOPLE. "But it will be a real pleasure to get back to living my life without seeing it in the news every day."