As young French couple Gilles and Marion officially separate, we see, in reverse order, the milestone moments in their relationship: Gilles revealing his unfaithfulness at a tense dinner party; Marion giving birth to their premature son while Gilles is elsewhere; Gilles and Marion's joyous wedding; and, finally, the fateful moment when they meet as acquaintances at an Italian beach resort, and their love affair begins.

Married couple Willy and Therese go separate ways. Willy leaves town and returns years later as a famous singer. But Therese is about to marry her best friend Peter. Little does Willy know that he and Therese now have a teenage daughter.