Chloe (2009) online

Catherine and David, she a doctor, he a professor, are at first glance the perfect couple. Happily married with a talented teenage son, they appear to have an idyllic life. But when David misses a flight and his surprise birthday party, Catherine's long simmering suspicions rise to the surface. Suspecting infidelity, she decides to hire an escort to seduce her husband and test his loyalty. Catherine finds herself 'directing' Chloe's encounters with David, and Chloe's end of the bargain is to report back, the descriptions becoming increasingly graphic as the meetings multiply.