A Severed Head

Antonia, the pampered wife of Martin Lynch-Gibbon, an upper class wine merchant, tells her husband that she is in love with their best friend, the psychiatrist Palmer Anderson. Palmer and Antonia want to deal with the situation in a civilized way, by remaining friends with Martin. Meanwhile Martin tries to keep his mistress, Georgie Hands, a secret, but Palmer's sister, Honor Klein, who taught Georgie at Oxford, tells Palmer and Antonia about her. (imdb)