What precedes Mitzi's seduction of Joe?

Mitzi leans toward her husband, trying to give him an eyeful of her cleavage. Her husband just continues to read the paper. Christopher didn't know how boring her days were, waiting for him to get home and notice her. Christopher mentions Joe, the new guy he's hired at the office. Mitzi wonders if Christopher is really that blind that he didn't know she'd already noticed Joe.