Responses

Author’s note (chapter 30.5) says that the series is 2 parts comprising of 5 big themes. Part 1 contains the first 2 - <Cataclysm> (ch 1-19 but they forgot to add the subheading) and <Act> (ch 20-30) focused on Yuri. Part 2 contains the remaining 3 themes focused on Jiri. I think <Deceit> is Jiri specific and probably involves upcoming backstory.
Have you noticed in this manhwa the "chapters" named "Deceit"?
Deceit <9> means chapter 9
Why? Maybe because both Yuri and Teacher are fooling themselves and don't want to accept reality (The marriage of their loved ones)