here's the plot from Asian Wiki Plot ~ Secret Love
Min-Hyuk (Ji Sung) was born into a wealthy family. He has everything including good looks, intelligence, but he doesn't have kindness. He loses his girlfriend in a hit-and-run accident.
Yoo-Jung (Hwang Jung-Eum) goes to prison, because of the hit-and-run accident that killed Min-Hyuk's girlfriend. Her boyfriend is the one that actually committed the hit-and-run accident, but Yoo-Jung took the blame. She is then betrayed by her boyfriend.