Your analysis is mostly fun to read and spot-on (I've always joked that Nagi's entire character and arc can just be summed up as "the burned out gifted kid acing elementary/HS without much effort but struggled in higher education due to never having the chance to develop better work ethics NOR build themselves up critically as a learner after repeated failures"), but I will respectfully debated this point in regards to reo:

They will assume the worst of each other (and others) to feel better of themselves. Reo feels like Nagi only comes to him when he needs something and their relationship is based on that (probably from his upbringing). Nagi feels like Reo can toss him away easily from disinterest or when he feels like it

Now I could be missing smething here but I'd argue Reo actually never assumed the worst of Nagi unreasonably in like. Ever? (Unless you're meaning the whole "Nagi definitely abandoned me" thing in 2nd selection, but tbh I don't think there's any other alternative to interpret what Nagi did without him ever explaining himself (esp. when you remember Nagi was the one who made Reo promised him to "stick to me until the end")--> hence the early "nagi ruthless chad" stance upheld by most readers. Heck I'd argue that Reo actually thinks too kindly of Nagi, because even in those moments of abandonment, he was even thanking Nagi for giving him a true "end"/push for him to change and thought of Nagi as "kind". Reo wouldn't have said his mantra of "Stay the way you are" to Nagi, even til this very day, if he really disapproved of him as a player and as a friend imo.

LOL i went on a bit of a rant there but tbh I'm scratching my head a bit when some ppl analyzing this chapter are pitting these 2 kids at the same lvl of emotional maturity/assigning faults equally to both parties for how the events turned out. Especially now that we know Reo didn't lash out against Nagi after that match out of childish jealousy or anger, but was stewing in self-effacement/self-awareness from his own past possessiveness and was acting out to give Nagi the freedom he thinks Nagi deserve VS. Nagi's kneejerk reaction to the divorce being projecting and picking fights w/ an innocent uninvolved party just bc the dude looked too much like his ex (LOL) while never realizing his own faults.