I think Manaka is going to slip up and fuck her ex. Another 50 chapters with this possibly being the start of Ueno and Manaka's exclusive relationship doesn't seem in the stars. The very fact that there's so much physicality left between the mc and the 3 bullies means he can't be locked down... Though I guess a break up arc is possible.
56 was supposed to be another major chapter. Will certainly know the idea of the direction of the rest of the story in a few weeks at the very least.
It would be disheartening to see Manaka do that after Chisaki's and Ueno's efforts to ward off Riku. I think what Ueno told Manaka in chapter 55 should give Manaka enough confidence to reject Riku's attempts of reconciliation for the time being. However, with
Riku reminiscing about his past relationship with Manaka, it is possible for him to convince Manaka to give him a second chance by denouncing his womanizing ways.
If Manaka sleeps with Riku this arc, Ueno would probably be demoralized in breaking his programming once he finds out the truth. Yet again, Ueno relapsed plenty of times throughout this story so if a distraught Manaka breaks down in front of him saying she failed, Ueno can comfort her by revealing his past failures and probably the truth about his own programming.
Like you said, looks like chapter
56 will be an important chapter, so fingers crossed!
