Destroy, She Said (1969)

In a secluded hotel circumscribed by a dense forest Max and Alissa Thor meet Stein and Elisabeth. Max, a professor of future history and an aspiring author, is immediately attracted to the brooding wife of industrialist Bernard Alione, Elisabeth, who is recovering from a miscarriage. Stein, a German Jew and potential writer, is infatuated by Alissa, Max's young wife and former student. During their sojourn the guests' identities gradually meld.