Not only has he started a relationship with best girl, but we just saw him have an important moment with another one of his female friends where they both accept the fact that they won't be together because he has made the choice that he wants to be Hamin. Although, they will stay close friends due to them valuing each other even after the girl becomes heart broken that they can't be in a more significant relationship.
We also cannot forget, he accepted the reality of him being a "Simp" by telling Sungah in public that he was the Ran Chat guy, even to the extent that he knew she would not only forsake him, but also be horribly disgusted by him. This was made apparent when she first accidentally found out his secret. This moment was purposefully done, so when MC told her himself, we the audience & he knew without any shadow of a doubt what her reaction would be, a reaction of utter contempt. Even knowing all that, he still told her, and accepted the consequences that followed it.