Ich bin die Andere (2006 Germany)

aka
I Am the Other Woman




Director - Margarethe von Trotta

Katja Riemann - Carolin Winter
Armin Mueller-Stahl - Karl Winter
Karin Dor - Frau Winter
August Diehl - Robert Fabry
Bernadette Heerwagen - Britta
Barbara Auer - Fräulein Schäfer
Dieter Laser - Bruno
Peter Lerchbaumer - Dr. Maiser

Deadly secrets begin to seethe when the irresistable allure of a
mysterious woman in red draws a weak-willed architect into a
fateful one-night stand... (Rotten Tomatoes)