@mammon - If she were doing it for the "sake of her friend" she would have let him know, or she would have included him; this is for herself. Much like how she called Yoshida over when he was with the Kouhai, her sole purpose is to separate while masquerading as "it's for mah friend". If it was a mature adult, and a friend you actually trusted, you wouldn't push them out of the picture. You would consult with them, form a plan, or at least ask if you could approach. Even Sayu was able to pick-up that Gotou was being fake. It's a total crock to say she's doing it for him.
Gotou just wants all the attention and doesn't want to share. Which is why when told she was the one who had to confess it was: "Teehee, wait for me" -- even though moments earlier she was willing to fuck him, and both their feelings are already out there.
This also isn't as much a consensual conversation as people are making it out to be. With their positions being what they are, Gotou has the power. Specifically because of the shit Yoshida's ass is on the line for. Sayu doesn't actually
know Gotou, but for the sake of placating her, she had to accept. Her discomfort is shown when the offer is made. Kouhai has been the only on handling this with any maturity. Consulting both of them, and putting her trust in her friend.
If we're being real, Yoshida is surrounded by shit, but only one has a legitimate excuse because of her age. People who don't like Gotou aren't saying it's not something that needs to be done; it's her approach, her reasons, and her actions prior.
If this happened to my friend I sure as shit wouldn't go behind their back. I'd offer them advice and see if I could help resolve the situation amicably. I would never have so little trust in a person I'd consider a friend to exclude them from something that involves their choices and their life.
Being "mature" means prioritizing your feelings
with logic. Not having to pick one or the other. It means taking the path that's best for all involved -- even at the expense of what you want. Thinking that removing feelings from everything in favor of logic makes you mature is what a child imagines maturity to be.