The Rules of Attraction (2002)

During a semester at New England's exclusive and ultra-expensive Camden College, a sexual triangle emerges between Sean Bateman, the all-American looking guy who deals drugs on the side, Paul Owen, who's bisexual, and Paul's ex-girlfriend, Lauren. Sean grows obsessed with the pure Lauren because he thinks she's passing him passionate, anonymous love notes. At the same time, Paul keeps trying to get Sean into bed, while Lauren pines for Victor, who she believes is her dream man despite the fact he is studying abroad in Europe.