A Woman's Decision (1975)

Original title: Bilans kwartalny

The main character is a bookkeeper, 40, who lives a quiet, uninteresting life with her husband and son of school age. She realizes that soon she won't be needed much at home as the boy grows up and the relationship with her husband crumbles. It's only when an embezzlement is discovered at the office and she stands up to her management, that she realizes life has more to offer. She meets a well-off former classmate, married to an American. Then she meets Jacek and starts contemplating possibilities of a new start. She discovers love for the first time, but turns to old ways rather than to break loose.