Sorry I forgot to add
Since Taeui's existence is source of luck in Jaeui's perspective. Once Taeui dies, Jaeui's bad health since birth will instantly kill him because Taeui's lucky charm quality is what keeps Jaeui alive.
just note Jaeui truly believes this
and further in the story when Taeui was truly in danger, they indicate how
Jaeui's luck saves Taeui, so that Jaeui does not die due to Taeui dying 🤣 (I hope you understood that last bit)