By Stephen M. Silverman
Updated October 28, 2003 01:00 AM

Mixed news in relationship-land: “Sex and the City” star Cynthia Nixon is single again, while MTV “Newlyweds” stars Nick Lachey and Jessica Simpson are commemorating their first year of wedded bliss.

Nixon, 37, and her companion of 16 years, photographer Danny Mozes, have separated, a rep for the actress confirms to New York’s Daily News.

“Cynthia and Danny were both growing apart,” the rep tells the newspaper, explaining that the two actually split last summer. “It was discussions they were having.”

The couple have a daughter, Samantha, 7, and a son, Charlie, born last Dec. 16.

The rep went on to say, “There was no third party involved. It was amicable. They are both committed and focused on the children.”

Meanwhile, Lachey and Simpson marked their first wedding anniversary this past Sunday in Atlantic City, N.J., where Simpson did a weekend show at the Trump Taj Mahal and taped some segments for Donald Trump’s new NBC reality show, “The Apprentice,” reports Launch Radio Networks.

As for first-anniversary gifts, Lachey, 29, told TV’s “Access Hollywood”: “We decided for our first anniversary we’re getting a new bed for our bedroom — that’s going to be our big anniversary present.”

Simpson, 23, added, “For your first year of marriage, the traditional thing to buy him/her is paper. I figure wood — you can make paper out of that, it’s close enough.”