While You Were Sleeping (2011)

Oh Shin-young is a hospital cafeteria nutritionist with a bright personality, who is happily married to Yoon Min-joon, who works in the sales department of a food company. But while giving birth, Shin-young falls into a vegetative state induced by the hospital's chief obstetrician Go Hyun-sung. Hyun-sung is Min-joon's ex-girlfriend who is still in love with him, despite being married to Chae Hyuk-jin, the director of a food company and Min-joon's boss. When Hyuk-jin learns of his wife's betrayal, he plans his revenge.