Why Hold Back the Truth?

Mi So suddenly faints as the memories of being kidnapped rushes back to her. As she lays unconscious on the hospital bed, the boy from 24 years ago who was by her side on that day, tells her exactly what happened that day. He had known all along who Mi So was, and now, he begs her to wakeup. Meanwhile, Lee Sung Yeon realizes why his brother, Lee Young Joon, never pitied his suffering because he knew all along it was him who was kidnapped and not Lee Sung Yeon. Mi So wakes up and bursts into tears finally knowing the person she had searched all this time is standing in front of her. But why didn’t he tell her in the first place?