My Little Bride (2004)

The only thing 16-year-old Seo Bo-Eun's grandfather wants is to see her wed; he even fakes a fatal illness to get his way. He arranges her marriage to 20-something Park Sang-Min, the grandson of a family friend. Keeping their marriage a secret from all but a select few, the newlyweds try to live their separate lives as normally as possible, but this soon becomes far more complicated.