Actors Michael Douglas, 68, and Catherine Zeta-Jones, 43, are splitting after almost 13 years of marriage. Was Michael Douglas' battle with throat cancer, and Catherine Zeta-Jones' battle with bipolar II disorder too much for their marriage to handle?

"Catherine and Michael are taking some time apart to evaluate and work on their marriage," Zeta-Jones' publicist, Cece Yorke told USA Today in a statement. "There will be no further comment."

According to People magazine, Michael Douglas and Catherine Zeta-Jones haven't been photographed together since April 22. They've also attended red carpet events separately, and vacationed separately with their kids, Dylan, 13, and Carys, 10.

Recently, Douglas has been relaxing on a yacht off the coast of Sardinia, while Zeta-Jones remained at home in New York, People magazine reports.

Douglas and Zeta-Jones have been married since their wedding in 2000, at Manhattan's Plaza Hotel in New York.

Douglas has since had to deal with his 2010 throat cancer battle, and Zeta-Jones has struggled with bipolar II disorder, People reports. Zeta-Jones had recently returned from a scheduled second round of treatment to monitor her bipolar disorder.  

"The stress has taken a toll on their marriage," a friend told People magazine.

Michael's eldest son, Cameron, was also sentenced to a five-year prison term on drug charges in April 2010, Fox News reports.

USA Today notes that another wedge that may have fueled the fire to their split is Douglas' comments about HPV possibly causing his cancer, which made it sound like she was the cause of his illness. However, he has since issued a statement clarifying that he was not saying he got it from her.

"They're taking a break," a source added to People magazine.