I strongly believe that Won was in love with Jinha, but also hooked up with his brother -probably because he wanted a distraction and also because Jinha and his brother was look alike. Jinha should be a student at that time and it's possible that he wanted to wait for him to be in a proper age so he confessed. And maybe the brother noticed that, so he caused his brother an accicent and that's how he got a memory loss -probably he knew Won in the past but he can't remember.
I strongly believe that Won was in love with Jinha, but also hooked up with his brother -probably because he wanted a distraction and also because Jinha and his brother was look alike. Jinha should be a student at that time and it's possible that he wanted to wait for him to be in a proper age so he confessed. And maybe the brother noticed that, so he caused his brother an accicent and that's how he got a memory loss -probably he knew Won in the past but he can't remember.