In All About My Romance, episode 15, Noh Min Young(played by Lee Min Jung) finally found out that Go Dae Ryong(played by Cheon Ho Jin) was Kim Soo Young(played by Shin Ha Gyun)’s father.
As Min Young refused to break up with Soo Young, Dae Ryong started to threaten her. He mentioned all the people she cared, and said, “If you’re really considerate about them, you’d better make a right decision.”
Min Young was confused and asked, “Why are you doing this to me?” Dae Ryong answered, “Because Kim Soo Young is my son. Will this be an understandable answer?” He continued, “That kid is threatening me that he will expose our relationship. He’s willing to sacrifice himself for you, Miss Noh. What do you think?”
Min Young was shocked to find out that Dae Ryong was Soo Young’s father.
Source : Koreandrama