The movie explores the often-unpredictable bond between the three main characters and how it intersects with their joint passion for professional tennis
Watts, 47, and Schreiber, 48, said that "the best way forward for us as a family is to separate as a couple."
Australian actress Watts, who has been nominated or two Oscars, and Schreiber, the star of "Ray Donovan" have been involved since 2005 and have never been married.
Watts had previously dated Australian actor Heath Ledger.