Last Night (2011)

When her husband Michael (Sam Worthington) has to take a business trip with an attractive female colleague, Joanna reacts badly (Keira Knightley). By the time he has to leave, he's assured her that nothing has happened and that he loves her.

When he leaves, she encounters a past love, Alex (Guillaume Canet), who invites her to dinner. She accepts and both she and Michael struggle with their fidelity over the course of 24 hours.