Elle court, elle court la banlieue (1973)

He is a sales rep. She is a secretary. They live in the suburbs but she works in Paris. They don't see much of each other and spend much of their time in commuter trains. They try desperately to change job locations to be more often together, but... The plot is not the important thing in the film ; what makes it emblematic of the early and mid-seventies is the insouciant atmosphere. The '74 oil crisis had not yet morphed into a recession, and life was good - even though it was as hard as ever to find a home near one's workplace (or the reverse) ! Marthe Keller and Jacques Higelin are both excellent. The movie is not an all-time great, but it captures the "zeitgeist" of French life in the Seventies.