Thank you so much @valNK chingu for the translation! This couple makes me so sad even though they only had 2 episodes with only a couple minutes of angst. I can't help it if their scenes are so powerful they get me every time emotionally.
I am SO glad they broke up, not only because we got that sexy kiss and more screen time for their reunion, but because fundamentally they had a problem in that Bora loved him, but did not yet see him as a man she can depend on. I think this is especially hard for Bora to do with any guy, let alone somebody 3 years younger who she always saw as a kid because of her identity as the eldest daughter. Like she mentions in episode 10, she grew up watching him for 18 years and always thought of him as her little sister's friend. Especially since Bora is wise beyond her age and had to mature fast, she probably thinks of him as way younger than her even though the age difference is only 3 years. I think she always felt pressure to be the supportive noona in their relationship which extends from her role as a noona to her brother and sister. Constantly, we see her giving him advice and helping him with his problems regarding his mom in episode 12 and dad in episode 14. However, when it came to her times in need, like when she was worried about her mom having cancer or when she was thinking about law as a serious career choice, it was hard for her to express her worries/feelings to him and she kept everything inside and only informs him of her decision. Even though we were supposed to see the part in episode 13 when she introduces him as her sister's friend to her friends in a lighthearted way, that scene was symbolic for her inability to see him as a man. I think that was Sunwoo's insecurity as well in their relationship because his persistency in trying to speak to her in banmal was just a disguise of his desire to be seen as the same-level as her in regards to maturity. He also always attempted to get her to share her career aspirations because he was trying to build that mature adult relationship where they can have those conversations regarding their future.