cause as much as it is a good story, they are both reaching the end of the school time and hitting a climax point. final or second to last are the best descriptions for something hitting those points, and being nearly 500 chapters long alone brings it there too.
take the things i was reading/waiting for updates and throwing them behind a paywall is how you get me to never use your service ever no matter how good it might be. you offer it up as a better alternative, not the only option.
that would be because the author took the story in two routes. the other route is also on the site, though not sure if it got hit too, where it comes to an end with them together. this is the timeline where things followed a more open path.