Three equally successful women will prove to be the unraveling of each of their so-called 'happy marriages.'

Song Won is divorced, a skilled literary translator of Chinese, and lawyer Sa Hyun's mature gym partner.

A Mi is single in her twenties and has spent the last two years shuttling between South Korea and the US in order to complete her studies. A shared airplane seat and a love of horses bring her and the doctor together. Add into the mix Yoo Shin's unusual relationship with his father's new wife, a classy, well-kept woman who raised him from childhood.

Dean Hae Ryoon hires the beloved actress Nam Ga Bin, whose career he has followed, to teach at the university, bringing the two in welcomed routine contact.

Mistresses aside, each couple has an Achilles heel that brings about much unhappiness, could trigger divorce proceedings, and leave them all wondering just how much happiness are we entitled to in life?

Sun Jae is a twenty-year-old piano genius who became a delivery man without finishing high school due to his poor background. One day, he delivers a package to a classical music concert hall, and he plays the piano positioned on stage. Sun Jae is found by Hye Won, an elite art director at the Arts Foundation and wife to a piano professor. Hye Won instantly recognizes his talent and sends him to lessons under her husband to cultivate him into a leading young musician.

Born to a poor family, Sun Jae had never taken formal music lessons and is overwhelmed by Hye Won’s support. Piano lessons are his salvation and she becomes his muse. One thing leads to another and he confesses to her, “I need you more desperately than music now.” Hye Won is deeply affected by his masculine charm and pleading eyes. Yet she cannot afford to throw away everything she has worked to build. However, it would be even worse to lose this young lover. Hye Won thinks to herself, “This is my punishment, for being ignorant of my feelings and arrogant in the face of love."