Girl for Girl (2001)

Ben and Jeff are about to take their successful Internet startup company public and hit the jackpot for which they have been working so diligently. Ben is dating a beautiful yoga instructor named Caitlin, while Jeff is seeing Sara, an ambitious model. However, the men decide that they are suspicious enough of their respective girlfriends' intentions to set up a little test of their fidelity, and each sets out to seduce the other's lover.