Everyone is ragging on FL, but to be fair, ML was really pushy with the passive-aggressive notes (the first one literally had a list of rules on it), and then went straight from that to putting up speakers (which he obtained specifically for that purpose) after only a few days to blast foghorn sounds into the other person's room. Like, it's pretty understandable that she'd be mad at him.
Sure, she did an about turn when she found out about his YouTube channel, but he flipped straight from blasting sound into her room to begging for not to spill his secrets and then let her deal with literally everyone else in the building.
Plus, he's the one who is insisting that she has to stay in the current living situation for the next few months and not ask her parents to sort things out, like that's a lot to ask of someone.