Adore (2013)

Naomi Watts and Robin Wright bring heavy hitting acting to this movie, which is an adaptation of a Doris Lessing novella.  The plot sounds tawdry, but the movie itself is more complex than the basics sound.

The setting is an idyllic coastline in New South Wales.  Liz and Roz are lifelong friends who have grown up there and lived all their adult lives in this place with daily sun and swimming.  They got married, each had a son, and while they are both employed, they seem to spend hours of leisure together. 

The bulk of the movie is set in a time when the women are in their 40's and the boys are in their early 20's.  One boozy night Liz' son confesses to Roz that he is in love with her (and frankly both women are in incredible shape--they have none of the sun damage that you would expect from a life at the beach, and their sparsely clad bodies reveal zero fat and hours of gym work).  She is not hard to convince, and they are off and running, having an affair while Roz' husband is working far out of town.  Roz' son discovers them and in what starts out as more of a grudge match than a love affair, starts to sleep with Liz.  The two women know that they have crossed a line--even though they are not technically related, the affair has an incestuous quality about it--and they know better than to go waltzing into town holding hands with each other's sons.  But try as they might, the attraction does not go away, and the ending is bittersweet at best.