I Like the Taste of Eating It Secretly.

Tae-oh, a self-employed veteran who has no intention of getting married, is unable to resist his younger brother's anger, so he asks to borrow the wife of a friend, Se-yeon, who works in insurance, for one day. Se-yeon agrees, thinking it might be fun, and as she sees Tae-oh living better than she expected, she gradually develops feelings for him.