Sarah Jessica Parker keeps secrets from her husband.

The 'Sex And The City' actress - who has seven-year-old son James Wilkie and 11-month-old twin daughters Marion and Tabitha with spouse Matthew Broderick - believes the key to a good marriage is to retain an air of mystery.

She said: "I like having some mystery in our relationship. I like not knowing everything about my husband. I think people should have things that are theirs, things that are the unknown to someone else. I think it's good to have some privacy and some secrets in our lives."

The 45-year-old star also claimed her husband has no problem watching her get intimate with another actor in any of her movies.

She told "We've been together for years. Both of us have starred in movies opposite lots of beautiful, smart, interesting people. But we have still come home to the same house, to each other. Matthew isn't jealous when I'm in a movie with a sexy guy. He doesn't seem to show any degree of being threatened by it. I don't know, maybe he doesn't care."