Parents need to know that this movie isn't appropriate for any kids under 17. This movie has extremely mature material, with very explicit sexual references and situations, including adultery, nudity, very strong language, drinking (to excess), and smoking. There are tense emotional confrontations that may be upsetting to some viewers.
I saw this film several months ago and found it vastly unsettling. A story of such infidelity between two couples that the very borders of marriage are blurred, peppered with harsh language and excessive drinking, I would strongly warn parents against allowing their children from viewing this until their late teens, if at all. However, to its credit, the acting is excellent, especially from the female leads, Laura Dern and Naomi Watts.