Sweet 18

Kwon Hyuk-Joon's grandfather, the head of the traditional Kwon family agrees to an arranged marriage between his grandson (Lee Dong Gun) and Yoon Jung-Sook (Han Ji Hye) when Yoon Jung-Sook is born. 18 years later, the two families lose contact because soon after the contract is signed, Jung-Sook's family encounters financial issues and is forced to run away.
Meanwhile, Jung-Sook has grown up to be a rebellious and strong-willed girl who just wants to live her life as she sees fit. With little aspirations, she is the direct foil of her achievement-bound counterpart, Hyuk-Joon. When the two meet each other, they clash horribly; Jung-Sook thinks her fiancee is nothing but boring, and Hyuk-Joon believes Jung-Sook to be nothing but an immature child. Despite all this they do marry. The rest of the series follows their life living together as a couple, and the obstacles they are faced with.