The student from Paris and his friends are intellectuals. He reads Le Monde. He is stamped by his background. The girl is in love with love. Everywhere she turns, there is love and passion evident, even through the hotel's thin walls. She only wishes to please and outwardly doesn't project herself as a self-regulated person. Her lower class background is clear before she goes on vacation where she meets the student. Although they stay in the same hotel, this is about the only thing they have in common beside the bed they share, but being removed from their normal lives just delays the obvious. Love is idyllic at first for everyone. She is hopelessly adrift among his friends in Paris and cannot communicate with them. This class based depiction is consistent with how many French view that one's birth divides a person from the other classes.
The class-based system exists here in the South, but I have a feeling that passion and love and familiarity more readily breaks down barriers than those 30 years ago in France.
This is a movie well worth seeing.