A Scent of Heather (1980)

A young girl, Heather has spent several years in a convent and raised by the sisters, and she knows nothing of men or sex. She marries, Frederick a man who is quite willing to teach her anything she needs to know. But at their first night they get a letter and learn that they are half-siblings. Thet separate their rooms. But she has several erotic encounters with the people around her with the help of Frederick.