IMHO, Grapara was cancelled not because of chapter 129 but rather chapter 129 turned out that way because the series had already been cancelled before. Maybe since chapter 127.
Timelines (assumption) of Airi Katsura (sensei) vs Kodansha :
-> Grapara was slated for ending in Volume 14 (around chapter 137)
-> To spite this decision, AK rushed the plot, having Sakura raped (or you want to call forced sex) and immediately switch boyfriends and agencies in chapter 129 and 130 to wrap things up by Volume 14.
-> She then paired Shinobu with Fumi and featured explicit love scenes in chapters 132–134 (her plan) to compensate the expected backlash from chapters 129 and 130.
-> However, the intense negative response impacted pre-orders for Volume 13 prompting Kodansha to intervene.
-> Kodansha offered a chance to redeem the series and postponed the cancellation.
-> AK then inserted Nagi into the chapter 132 though it upset readers who felt the love scenes were being interrupted.
-> Then Nagi and Mio comforted Sakura in chapter 133 seemingly in an attempt to make it appeared as though Sakura wasn't actually dating a fucboc to reduce the hatred towards Sakura character.
-> Because readers loathed Sakura (and fucboy) so intensely that attempt to rehabilitate her image failed.
-> Consequently, Kodansha ordered the series to end early to prevent further damage and also cut the loss.
-> AK revised the plot to reveal that Sakura was still dating the fucboc and made her become a truly villain having a new boyfriend without telling Nagi or Mio which caused Shinobu to face unfair backlash. There is no need to correct the Sakura's image anymore.
-> To appease readers, we can expect that Kodansha will add chapter 133.5 featuring a full sex scene between Fumi and Shinobu. They can order Keishi Nishikida sensei to draw it without AK's help.
-> As for the ending, we don't know what Kodansha told AK. It could a drastic scenario like Sakura committing suicide to escape her problems because this character is already dead for readers and readers want to see her pain. There are only two chapters left. Maybe another way is to use a nonsensical time skip.
Airi Katsura (sensei) never said "sorry" and Kodansha did not stop her from quarreling with readers because Kodansha had already cut ties with her ! The decision to part ways had been made before chapter 129 was released. So, there was no longer any need to protect her image given that they would not be working together anymore.
However, After the end of Grapara, what we know is that Airi Katsura (sensei) has been blacklisted by the rom-com readers already. Her reputation in the mainstream manga industry is ruined, leaving her only adult/underground work to do. So sad but she destroyed herself. I hope her family member will take her to see a doctor as she might be suffering from a mental health issue.
P.S. The best part for me is getting to discuss things with everyone here. Thank you so much. it’s honestly way more fun than reading Grapara manga. LOL
