The Affair (2019)
Liesel Landauer and her friend Hana are linked by a lifelong relationship and are having an affair even if Liesel is already married to Viktor in Czechoslovakia in the early 1930s.
Actors: Karel Roden
Parallel Worlds (2001)
A woman’s live-in boyfriend has a mistress. She has revenge sex with a friend’s husband.
Guard No. 47 (2008) aka Hlidac c.47
A wife makes the mistake of starting an affair with an insecure, young, annoying beta prick.