'Vicky Christina Barcelona'
While it's technically a comedy (by Woody Allen, but we'll ignore that part), Vicky Christina Barcelona is really sexy. First you have the two Americans, Vicky and Christina, who are in Barcelona for the summer, where they meet Juan Antonio. Each one separately has a fling with him, then his ex-wife, María Elena, comes into the picture when Christina has moved in with Juan Antonio. Then, the three proceed to have a polyamorous relationship. It's as sexy as it is funny. Also, everything is sexier in Barcelona.