It's a film from the last 15 years. I think it's set in Canada to begin with. There's a scene near the beginning of a dark haired 30ish woman getting ready for a party. She seems tired and maybe cynical. At the party, she meets a tourist/immigrant (from France or Algeria?). They spend the night together. He's returning to France and leaves her his number. She's all angsty about everything, and her sister ends up convincing her to follow the guy. The woman and her sister go to France only to realise they've lost or forgotten the man's phone number. Just as she's about to return home, she runs into the man on the subway/bus.
