CNBLUE's Kang Min Hyuk becomes jealous when he finds out that Oh Yeon Seo has started dating somebody else right after their breakup.

On July 8, the 40th episode of KBS drama "Unexpected You" featured Cha Se Gwang (Kang Min Hyuk) asking to speak with Bang Mal Sook (Oh Yeon Seo) after finding out that she has been taking out her anger on his older sister, Cha Yun Hee (Kim Nam Joo) and her husband.

When they broke up, Cha Se Gwang had told Bang Mal Sook that the reason for their breakup is his family's strong disapproval of their relationship. Even though she accepts the break up and tries to move on, she takes her anger out on Bang Gwi Nam (Yu Jun Sang) and Cha Yun Hee.

After learning about Bang Mal Sook's inappropriate behavior, Cha Se Gwang tells her, "What happened between us is between us. Is it really necessary to behave that way in front of my sister and her husband?" to which Bang Mal Sook replies, "This is my way of trying to give up on you. I need to make myself look even worse in front of your sister and mother to make them hate me more. That will be the only way to keep myself from wanting you."

Bang Mal Sook then shows Cha Se Gwang her diary and says, "This is a guy I used to date a while ago. I'm seeing him again. I'm so busy these days that I barely have time to cry over you. I was so caught up in you that I wasn't even myself but this is the real me now. I'm successful and busy, not to mention all the guys who are in line trying to date me."

Cha Se Gwang, who was about to open up to her gets angry after hearing her words, says, "How long has it been since we broke up... and you're dating somebody else already..." and starts to become jealous and disappointed.