You never know what's going on behind the candelabra.
Douglas left their Bedford, N.Y., estate 18 months ago for a bachelor pad a few miles away and now spends the majority of his time at their Central Park West home in Manhattan, N.Y., E! News has learned.
"He loves it there, it's where most of his friends are, and he can go about his business in privacy," says a source. "It's not [Zeta-Jones'] bipolar episodes that have driven them apart, it's just happened naturally. They like different things. He likes the city, he only moved [to the suburbs] for her, as she loves horses and playing golf."
In fact, Zeta-Jones was spotted Aug. 6 at a local stable and driving around in her Porsche SUV with her mother, Pat.
"Apart from riding and playing golf, she's quite happy hanging around the house or going shopping," the insider continues. "She spent a fortune in the local Pier One last month and has even visited TJ Maxx."
The source added that, while Zeta-Jones has "a few friends in the village," she's never spotted out with other celebrities who live in the area, such as Glenn Close, Martha Stewart, Susan Sarandon and Richard Gere. "She keeps to herself," the source says. "She'll only ever be seen browsing in the bric-a-brac stores, clothing boutiques or at Sunnyfield Farm. She even gets someone in to do her nails and hair so she doesn't have to go outdoors."
But when she does interact with her neighbors, the insider added, "she's always very pleasant to people."
Douglas, who's been spied at the local movie theater with Gere before, will "walk around town in a baseball cap and no one will disturb him. He's well-liked in the community," the source says.
He and Zeta-Jones have two children together, 13-year-old son Dylan and 10-year-old daughter Carys.
"They're like chalk and cheese," our source says of the estranged couple. "The only thing that really bonds them is their love for the kids. But even then, they do it separately."
"Michael will spend a lot of time with Dylan playing sports" and "Catherine dotes on daughter Carys. They often go shopping together in the local stores like Bubble and Treat, or go riding together. She's got a horse at Sunnyfield Farm, along with her daughter who's into [riding] as much as" her mother is.
As for the bachelor pad Douglas had been staying in, it was a converted barn (converted into a four-bedroom, three-bathroom home, that is) situated off the main road on the grounds of a pal's $15 million estate.
But some acquaintances of the couple insist that they are "definitely still a couple" and recently attended a local fundraiser together for a cancer charity Douglas supports. They were last photographed together in April at the 40th Chaplin Award gala at NYC's Lincoln Center.
"There seems no obvious reason to get divorced," a source says. "They both get to do what they want privately."
—Reporting by Michelle Falls