
Ngl, even though the 'inviting the ex over to drink and ends up getting drunk' thing is for plot progression, it still seems out of character for him, he won't do something like that. He's not the desperate type

Since I have had a few weeks to think about this chapter and know the next few chapters. I think Hajin is really messed up inside and not thinking thinks through. That is why he was going for alcohol before Jaehee showed up. I was mad because Hajin already set the boundaries and it is totally out of character. I think Hajin did not want to be alone and Jaehee was convenient. Too bad he didn’t call Woojae instead or just get alcohol and go back home to drink alone.
The MC is the pompous personality type that I hate the most, but I'll keep reading because the story is well written.