Responses
I def think it was good for Taejun to get his ego checked, even if it's bc of a lie. He's starting to realize that his fuckboy behavior can have a negative impact on someone he cares about.
Hopefully he'll also learn that it's wrong to view Geonwu as this ~super special~ person who will never lie to him or let him down. Geonwu isn't an emotional support bestie, he's a regular person who has his own life/worries/flaws just like Taejun does.
THISSSSS
I could hear his heart breaking and feel his anger building. He probably feels embarrassed because he thinks he overestimated his importance in Geonwu's life.