"Sex and the City" star Cynthia Nixon's relationship with partner Christine Marinoni is "fantastic" and she's "in love," the actress told reporters while promoting the upcoming "Sex and the City" movie.

Nixon has been with Marinoni, a New York City education activist, since 2003. That year, Nixon separated from her boyfriend of 15 years, Danny Mozes, the father of her children Samantha, 11, and Charles, 6.

"I'm in a fantastic relationship. It's been about four years," Nixon, 41, said. Read more: 'Sex and the City' Star Cynthia Nixon Discusses 'Fantastic' Lesbian Relationship