The A-list couple - who have been married for 13 years - haven't been photographed together since April and have been taking separate holidays with their children, Dylan, 13, and Carys, 10.
Catherine's spokeswoman tells Reveal: "Catherine and Michael are taking some time apart to evaluate and work on their marriage."
Recently, Michael was seen relaxing on a yacht in Sardinia while Catherine remained in New York.
Aside from her marriage difficulties, Catherine has been going through a particularly tough time this year, as she voluntarily checked herself into a health care facility in April to seek further treatment for her bipolar disorder.
This wasn't the first time the Hollywood couple have been hit with health concerns either, as Michael was diagnosed with throat cancer in 2010.
He announced that he had beaten the cancer in 2011 following successful sessions of radiation and chemotherapy.