
so when is at gonna actually be about the main pair lol is 704's relationship with geumsun and the underworld or whatever THAT important that they take up most of the story ?

Arguably San and Eunjae would not be an important part of the story - or even at all part of the story, actually - if not for Geumsun. Hwan doesn’t want to eat San or Eunjae just because they’re tasty. He wants to eat them to regain his strength as quickly as possible to get revenge on Geumsun. So to care about the plot of the story (why Hwan must be defeated) we have to understand their motives and for Geumsun all of that is wrapped up in his relationship with 704. Without any of this context it would be hard to be invested in the conflict.
Listen, I love San and Eunjae too but their happy moments alone isn’t going to drive the plot forward. And if you recall the author’s note at the end of season 1 it was stated that all four were main characters and both relationships were going to have equal time to develop in different ways.
So yeah, I’d say 704’s relationship with Geumsun is pretty important. And the underworld too, obviously, because that’s the whole setting and what’s at stake?
That said, I totally get being frustrated. Personally for me is anything other than Yama really important here? Haha jk. I hope the rest of the story grows on you though!
nobody's gonna tell him about his two whole ass kids?