As Good as Poison (1986)

Engineer Pavel Hnyk is successful at work, but not very happy in his private life. He is approaching his fiftieth birthday and he can't shake the feeling that life is slipping away from him. The most effective medicine for such woes is amorous adventures, and Pavel indulges in them. His wife Alice is a lawyer by profession, so she knows about such cases, and because she is a wise woman, she passes them over in silence. One day, however, a new colleague appears at Pavel's workplace - the charming Slovakian Julie. A friendly relationship soon turns into a love affair, and over time it grows into a headless, destructive passion that cares for nothing and no one...