I Think I love My Wife
(2007)

Nikki (Kerry Washington) gets engaged and invites Richard (Chris Rock) to her apartment before the wedding for a "proper good-bye." They begin to get into it, but when Richard takes off his tie, he sees his reflection in the mirror of what he does when he plays with his daughter. Richard storms out of the apartment, comes home to an alone wife, and reignites the spark in his married sex life.

Thanks Herbert!