They are teenagers.
(Spoiler free)(P.S.: Maybe this is incredibly common in anime/manga communities, but im new to this stuff)
People here seem to act like the characters should be perfect, I get that a lot of it is joking, but some people take this viewpoint seriously. Part of what makes RoI and other anime so intriguing is because your attached to the characters, and you see them weave their way in and out of conflicts. Of course we have the power of retrospect, so we think "they should have done this, they shouldnt have done that" or "they shouldnt have this trait or act like this". they are teenagers! Smarter than real life teenagers, but still teenagers! Thats what makes teen rom coms so interesting, its with the added idea that they are still becoming themselves.
Maybe im overthinking it
Im probably overthinking it.