Trois (2000)

Jermaine is a young corporate tycoon who is newly married and has recently moved to Atlanta, Georgia with his lovely and supportive wife Jasmine. While becoming settled into the new city and job, Jermaine becomes bored with his seemingly mundane lifestyle at home. He asks his wife to engage in a menage a trois with another woman, in order to generate more excitement within their relationship and she reluctantly agrees. Once they've committed the act, Jermaine begins to feel the insecurities of bringing a stranger into his marriage. As a result, he attempts to sever all ties with the woman. Unfortunately, it proves more complicated to remove this person from their lives and he realizes that his curiosity has thrown him into battle with a dangerous lunatic and may cost him his marriage.