"Catherine and Michael are taking some time apart to evaluate and work on their marriage," a rep for Zeta-Jones said in a statement on Wednesday.
Their relationship reportedly started to dissolve after the stresses of serious life events took a tool on their relationship.
Douglas successfully battled throat cancer in 2010 while Zeta-Jones has struggled with a bipolar disorder for which she's twice sought treatment in 2011 and again in April of this year.
Douglas and Zeta-Jones have not yet officially filed for divorce. The couple have two children: Dylan, 13, and Carys, 10.