Oh, please. How is it any of your business that he's living together with a girl? It's not as if she's even close to being in a relationship with the mc. I never really understand the logic of these unreasonable characters in manga...
What's happening in this manga? It was so nice initially and quite a good read, but the further along we go, the worse it gets and the more annoying characters become. I'm starting to actually dislike this girl. This is absolutely none of her business. Also, she has NO RIGHT to go through someone's house or drawers and "inspect it". Imagine if someone did that to you, you'd freaking kick them out and break off your relationship with them. Everyone has secrets or things they don't want people to see. Only a true asshole wouldn't respect this basic right of privacy. It's ridiculous that they're tolerating her shit. If she was inspecting things in school, that'd be fine, but this is outside school in a private apartment, she has no right to inspect anything and no matter what he's got in there, she has no right to comment on it either.
Why are they tolerating this? Why isn't he talking back and telling her to stop properly? You need to establish some lines and your own authority in your own home. He clearly hates it, yet he allows her to do this shit as if she's his mother or something. She actually actively looks for the stuff he doesn't want her to see, like erotic books and other shit. Reprimanding her harshly and telling her to get the fuck out and realize her place isn't enough at this point, just stop talking to her altogether. She brought it upon herself, she has no one but herself to blame, perhaps she'd be able to grow up and mature a bit if that happened.
Remember, kids. Respect other people and their privacy, after all, you wouldn't want someone to go through YOUR OWN dirty secrets. Imagine her reaction if he went into her room and ransacked it for sex toys and erotic material. Then, all of a sudden, it wouldn't be considered as okay to her anymore. Give me a break, treat other people as you, yourself would like to be treated. Without respect no one will want to be your friend, much less girlfriend/boyfriend.
I wonder if it's too much to ask for to get a mc in a japanese manga that actually acts like a human being and not like a doormat which the females can step all over without him retaliating despite being deeply wronged over and over again. Are all of them ball-less, cowardly masochists? Any remotely human being would snap and become really pissed off if someone did this shit to them, if that doesn't happen, how could I like the mc? He's just acting like a pussy, and the worst kind at that, the indecisive and wishy-washy type.