Nagi being the victim of Reiji's suitors abuse is an inherited theme from the flashback namek where Esemori was the victim of Yuko's suitors (namely Uryu's gang and rival gangs) harassment. It's the cycle of town's people trying to keep people apart. And it's also the main plot point of Esemori's novel, the couple that commit suicide as a way to escape from everything because novel's MC was the target of the town's abuse because all of them wanted the novel's FMC.
There are 3 roles that get repeated in present time, in the flashback namek and inside Spring's coffin (the novel)
The girl and trophy the town wants: Yuko (both Reiji's mom (past) and Spring's coffin FMC), Reiji (present)
The outsider town's girl gets smitten with and is victim of The Town's abuse: Eita (Spring Coffin's MC), Esemori (past), Nagi (present)
The people who want the trophy and keep the MCs apart: the town suitors (Spring's coffin), Uryu, Minegishi papa, Shino'oka (past), Yuri, Gen, Chako (present).
Now, and thanks to the spanish translator who gave me that insigjt, story isn't running in circles because fuck yeah, but because there are situations and leitmotifs that are getting repeated and mistakes from the previous generations that should not be repeated by the new generation. The risk of Reiji and Nagi severing ties on badly ill terms just like Akira and Yuko is quite high if we consider Nagi is being subject of abuse and criminal shit because of Reiji and people wanting Reiji, therefore, Nagi could end being possessed by the horror and blame Reiji for all the fluke. Just like when Akira got horrified after murdering Uryu and blamed Yuko on such a tragic fate, on all the shit he had to endure in that town, and told Yuko those condemning words. Something he came to regret forever and only after the flashback Reiji made him realize the actual truth... then Yuri told him what he should have done instead of running away.
However... Nagi should not blame Reiji because, let's be honest, she initiated all of this. But at least this generation at least is trying to amend their mistakes, from the previous one, only Shino'oka could come out of her abyss because she came honest with Esemori after being cucked. Nagi apologized for having invited Reiji to commit suicide and lacks Esemori's spitefulness, Reiji failed to become fully like his mom and feels guilty for having wanted to turn Chako into his new Nagi despite of having drowned Yuri into his issues, something he may end up feeling guilty for too, Gen voluntarily got hospitalized into a mental faccility and realized he was just another victim of Yuko's manipulations, and Chako realized what her selfish actions caused to her environment. The only one who may end up having an ominous fate is Yuri by being kind of an Uryu stand in in this story (the lover that gets drowned into the Kurose's abyss out of Kurose's abandonment).
The solution for Reiji and Nagi's abysses it's something i'll explain when the next chapt. gets posted.