Michael Douglas and Catherine Zeta-Jones during better times.

Michael Douglas and Catherine Zeta-Jones during better times.

Michael Douglas and Catherine Zeta-Jones, one of the great, if quizzical, Hollywood marriages of the past decade, are apparently teetering on the brink. It’s still unknown whether a divorce is in the works, but the duo have been living separate lives for the past six months and maybe longer.

It’s an odd twist for Douglas who suffered through a dysfunctional, 23-year marriage to first wife Diandra Luker, whom he divorced in 2000.

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She was only 19 at the time they married and he was 32. His marriage to Zeta-Jones is also a May-December union. When they were married in 2000, weeks after his divorce was final, he was 56 and she was 31, a 25-year difference.

He was only a television actor when he married Diandra in the 1970s. But by the time he married Catherine, he was an A-List actor with a Hollywood pedigree; his father is Hollywood legend Kirk Douglas.

People reported in its latest issue that the couple has made public appearances and vacationed separately in the past several weeks. Douglas is reportedly on a yacht off the coast of Sardinia. Zeta-Jones, who loves yachting on the Mediterranean, is still in New York.

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But the credit for “breaking” the story goes to The National Enquirer, which has been harping about trouble in the marriage for the past year. The magazine came out with a fresh report this week, claiming the couple is heading for a $300 million divorce. If true, it would be one of Hollywood’s largest.

Michael set a record (since broken) back in 2000, when he shelled out $45 million and gave up his Santa Barbara estate in his divorce from Diandra. She subsequently sued him in 2011, seeking a cut of the profits from his “Wall Street” sequel “Money Never Sleeps.”

Douglas lambasted the Enquirer’s reports, but now the operative explanation is “they’re taking a break,” according to a source. So far neither has filed for divorce.

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Their children, Dylan, is now 13 and Carys is 10. “They want the best for their kids, no matter what happens,” the source says.

Insiders say the marriage has been under strain ever since Douglas was diagnosed in 2010 with stage-four throat cancer and Zeta-Jones went public with her struggles with a bipolar II disorder a year later.

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There may be a good reason for their separate lives at the moment. Douglas, now 68, and Zeta-Jones, 43, continue to work as hard as ever, leaving little time for their relationship.

Last year, she appeared in “Lay the Favorite” with Bruce Willis, “Playing for Keeps” with Gerard Butler and the film version of Broadway musical, “Rock of Ages,” co-starring Tom Cruise and Alec Baldwin.

This year, she appeared with Russell Crowe and Mark Wahlberg in “Broken City” and starred in Steven Soderbergh’s “Side Effects,” with Jude Law and Rooney Mara.

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Douglas has appeared in the film “Haywire” and starred in his highly publicized role as Liberace in HBO’s “Behind the Candelabra.” He’s also been filming two other movies, “Last Vegas” and “And So it Goes” and is slated to appear in “Tragic Indifference,” about a lawsuit against Ford over a tragic SUV accident.