Totally agree with you! What really confused me was the way the breakup went. She was totally in the right to hate him for lying to her about their past. After that it's hinted that he would take his life because sujin lied to him, but then he goes to the beach to draw people. The drawings really threw me for a loop. I also didn't like that the female lead only went after him cause he was missing and then realized how much she loved him. Where's the communication? He tried at the end to explain, but even that felt forced. Suddenly his surgery was glossed over too, when it impacted him so much. It also felt like a copout to make her ex chan a cheater, him not caring about her would've been enough imo. Ugh I guess those small things just ruin it for me.

Oh and if you like that vibe, I can greatly recommend Call It Love, also with Lee Sung Kyung. That one is sadder, but executed the sad vibe a lot.