I was wondering the same myself, then I realize the description says chemistry. Doesn't really mean end game and perhaps the author made that clear in ch4?
Either way guess we need to wait more for someone who loves the main cast to death to give Sensei the proper ending she deserves, or we can wait for 22i. For whatever reason having sensei as the last girl must mean something. Even if the overall story doesn't have the same vibe, I feel having a mainstream ending for a Sensei must inspire other authors. Senseis also need love dammit!