Adore (2013)

Lil (Naomi Watts) and Roz (Robin Wright) are two lifelong friends, having grown up together as neighbors in an idyllic beach town. As adults, their sons have developed a friendship as strong as that which binds their mothers. One summer, all four are confronted by simmering emotions that have been mounting between them, and each find unexpected happiness in relationships that cross the bounds of convention.