Every chapter has had a misunderstanding, The blond girl is a stalker, the mc just blindly goes along with everything she does, she breaks into their house(which they're only guests at) and sneaks into his bed, and this is supposed to be someone he hates yet doesnt even care about it anymore while not asking a single question to clear anything up. If the blond wasnt in the story at all and it was just about the mc and his sister going through life with him slowly getting with the black haired classmate that obviously has a thing for him, this manga would be top tier. Unfortunately it's focusing on cliche tropes to drive the story as much as it is with the development between the mc and his family.