Fox reportedly was the one who decided to separate six months ago. The couple have two children together, Noah, 2, and Bodhi, 18 months.
Things between the couple "have been rocky," one source said. Though the insider didn't specify the cause of tension, there have been rumors that Green would prefer Fox to spend more time at home rather than working.
Fox and Green met on the set of her sitcom Hope & Faith in 2004. They became engaged in 2006, but called it off after three years. In 2010, Green proposed again and they tied the knot 24 days later.