Variety.com said Gosling and Williams are to play a couple reflecting on happier times while their marriage disintegrates.
Written by Derek Cianfrance, Cami Delavigne and Joey Curtis, and directed by Cianfrance, the movie co-stars Mike Vogel, John Doman and Maryann Plunkett, the entertainment industry trade newspaper said.
Gosling's film credits include "The Notebook," "Half Nelson" and "Lars and the Real Girl."
Williams has starred in "Brokeback Mountain," "The Station Agent" and "Synecdoche, New York."
Gal Gadot cast as Wonder Woman for 'Batman vs. Superman'
Beyonce flaunts bikini body, Blue Ivy in vacation pics