Yes but I was talking about malicious intent. There is virtually none of the usual "you are not good enough for Sachiko-sama" type of bullying, tacks in her shoes, books thrown away type of thing you see all too often. It would probably clash with the period feel Nezchan was talking about above, granted. That does not make it any less refreshing to be spared of almost all antagonism in the entire series however, be it by peers or relatives.
In fact, there is only one volume, or one episode of the anime, I can recall where the latter group does try. At that point though Sachiko and Yumi's relationship is already too strong to break with such petty tactics, and the whole thing ends up playing so beautifully that it honestly is one of my favorite parts of Marimite. Such a great turning point moment after the preceding drama in the series, and the first time that Sachiko and Yumi felt like equals really.