There isn't no clear reason given as to why the mother is lethargic and anti-social but  it sure gives a lot of pressure into the girl.  This for me is heartbreaking and the unconventional relationship of mother and child seems like there is a big wall between them.  There are a couple of scenes with blurred backgrounds  as if to give a limit to the details that the viewer can see and this was also observed during the school concert scene.  I think it was intentional, to highlight the expressions and facial  nuances of the girl who was really hoping to see her mother there.  The  last scene, where the girl plays outside and the mother looking out of the window was  a poignant scene but  I think it lacked impact and emphasis.  Was it an indication of an improved  relationship?  Did it signify anything positive?  I felt as if there wasn't but then again, maybe the scene was also an implication that something in her mother was awakened,  to the point that it will  wake her from her lethargy, hopefully.  Impressive cinematography,  acting was  at par although  it can still be improved.