Escapism (1966)

A middle-aged doctor and his young assistant are both smitten with a girl. The girl likes the doctor's assistant, but the doctor, who is deeply in love with the girl, sends the assistant away on some pretext. He then gets closer to the girl and, with the support of her parents, marries her. They have a peaceful life until the assistant returns and the truth comes out. After a series of events, it's ultimately the doctor who steps aside.