Yoon Jin is somehow saving Sun Woo's live. She never confirmed her feelings for him because then it would be dangerous not only for her but for Sun Woo. It is better to play it safe by letting them believe she is just following orders. No feelings attached.
But her betrayal cuts deep on Sun Woo. After releasing her and walking out of the apartment after he handed the hard drive, she could no longer pretend in front of Sun Woo. Her guilt is so strong she needed him to know and stay focused on living or fight his own battles. She wanted out because soon she will be reunited with her family. It was a promised after securing the hard drive. They will all go home.
Sun Woo was shocked learning the deceit. He strangled her but he let go in the end. After all this woman is the one he loved. He asked if she really loved him but she denied. She cried alone. Determined to stay away. Sun Woo went Gi Chul's hide out but no longer there. There were dead bodies, one was the man who got the hard drive.
The plan to kill Gi Chul and Hye Rim both backfired. The group were divided and Gi Chul's men over powered the other half. Their loyalty was with Gi Chul. Gi Chul shot the man. He learned his lessons well form Hye Rim/Sung Hye. He got her hostaged by his side as he went to her husbands office to decipher the code.
Sun Woo was almost caught inside the building with the dead bodies. He grabbed his mother's bag and pretended to be a delivery man just as the police came. One followed him as he seemed suspicious but he dealt with the police silently. He looked for his mother. He followed Yoon Jin who by that time was on her way to the airport. She changed into the rest room. that's where Sun Woo cornered her. He even fought with her. He needed her to know where his Gi Chul is. But at the same time, I think even after learning she betrayed him, he does not want to let her go. He dragged her to his father's office. He alerted his team who were looking for him to head at the office. he did not know that there was an order to kill him coming from Song Joong Hyeok.
Meanwhile HyunTae found out that the man he was looking for was already dead.
Next episode would be bloody if the NIS team arrived at the scene.