As Valerie, 19-year-old Virginie Ledoyen is not just the titular Single Girl, but for all practical purposes, the entire movie. As the film opens, she meets her sullen, unemployed boyfriend Remi (Benoît Magimel) at a cafe, and reveals that she is pregnant with his child. She is not only unsure about whether she should keep the child, but whether Remi would make a decent father if she did. She is also starting a new job as room service in an expensive hotel and promises to return to the cafe in an hour and tell Remi her decision. The bulk of the film consists of a real-time study of that critical hour. Valerie takes trays from room to room, and the camera follows every stair step, every elevator trip. There are interactions with peculiar guests, but none of them are particularly important characters. The focus is always on Valerie.
~ John Voorhees, All Movie Guide