Responses
Yes, nothings wrong there.
Its pretty simple, yet complicated at the same time. Former Heewun's existence is deleted by author, hence why nobody can see him. Jihun is only demoted to extra, so he still exists within the story.
Old story characters:
Jihun x Heewun (old)
Revamped story characters:
Geongju x mr. Big Dick (forgot his name, sorry) x heewun (new) (+ the black haired new uke)
So, Jihun now chases after Heewun (new) because he thought heewun forgot his love for jihun. Meanwhile, jihun isn't aware that it's heewun (new) and he doesn't have any feeling for jihun in the first place. And Heewun (old) is still there but he can't be seen.
I didn't miss anything right? It's so confusing...