Holy fuck does the lesbian bitch suck! You know, I'm all in for her plan of separating the MC and the blondie so he can be with the tomboy, but being the useless cunt that she is I know all her shenanigans would accomplish nothing but making the MC's life harder and pissing the readers off, and maybe even make them closer to each other. What a pointless and shitty character.
The teacher is acting way more problematically. You just don't chew out a student that is in the Student Council for less than a week because he filled a report wrong.
You either bring the report to the hierarchy, in this case the president, and ask why she didn't notice it was wrong (which is her responsibility as his superior) and you explain calmly what is the problem.
Blaming and shouting at a newby for newby mistake disqualifies you as a teacher in the first place.