(entertainmentwise.com) - Cynthia Nixon is making plans to `marry' her partner Christine Marnoni after beating breast cancer .The Sex and the City star, 42, underwent surgery and six-and-a-half weeks of daily radiation treatment after she was diagnosed with the disease in 2006, and the experience has prompted lesbian Nixon's desire to cement her union to Marinoni with an official declaration of the couple's commitment to one another.A source tells the National Enquirer: "Cynthia and Chris want a quiet autumn ceremony in Vermont under the red leaves."It's supposed to be a very low-key gathering, just for close friends and family."Nixon met Marinoni in 2004, just seven months after ending her 15-year relationship with former lover Danny Mozes, the father of the actress' two children.