I mean sensei is only doing the stuff he does because we make him do it, he really just seems like someone's who's reading from a script and enjoying the physical aspects of the job even if he doesn't fully understand the world he's been dropped into. The player's calling the shots, deciding whether or not to betray Rin for example, he's just along for the ride and enjoying the constant sex.
The story is self-aware enough that it wouldn't shock me if we as players are considered characters on some level and addressed directly as such.
Edit:
Hopefully foreshadowing
I have to agree with
kekkerino123 on this for both his reasons and some of my own, I mean you can say the player is the one calling the shots on EVERY game since no game acts without the player's action, but that is not what is going on here. While we are the ones that make the choices when they are given, any choice made in text only, meaning not in an interactive form like a set of buttons, is fully made by Sensei in the story. You also didn't account for those cases where actions like betraying one of the girls are split between builds. If the action that betrays the girl is added before the betrayal was even possible and the player takes the option that betrays her, that takes the choice out of the player's hands. I've said it before and I'll say it again, if I had had the choice not to betray Rin in the build where Schadenfreude was added, I would not have completed Schadenfreude until it was no longer a betrayal, not because I don't like taking what is offered, I'm an evil bastard myself and love taking what I want, but because this is the one game where I couldn't do that to the characters. I'm still trying to understand that effect myself, honestly. The only reason I ended up betraying Rin was because I had already triggered the Schadenfreude event when the beach event was added and that meant my save was an automatic betrayal that I did not intend. Yes, Sensei is enjoying the physical aspects, that was his goal from the beginning, to take advantage of the girls. It is only in more recent builds that we are starting to see a change that he himself has acknowledged.
I believe that these scenes about you losing control have another reason. Like during the scene with ami where you visit her parents grave, the MC says a few times that he kinda of lost control of his body/mouth. that along with the events you have pointed out. make me think that the original sensei is still inside his body seen everything that you/MC are doing. i think we might see a internal conflict between MC and the original sensei eventualy.
That could potentially be the catalyst for this change we are starting to see him going through.
