There is a meaning behind mother's strict behaviour. "She loves you, no matter what will happend, even she feel your loneliness and it's painful for her."
This kinda feels like the plot to a kids film condensed into a single chapter.
@pandascepter I don't think that would really apply to genuinely terrible parents. But that doesn't really apply here since this is just a simple case of the parent giving more attention to the younger child, and the older one getting just a bit jealous of it.