Is the physically able to smile?

It seemed that the main character "Lynn" was in a permanent, unchangable state of complete and utter discontent, unhappiness and deep sorrow for the entire length of the movie. I didn't see her remotely content for even one single moment, and after a while of watching it dawned on me that every time she appeared, I became uneasy, as the expression on her face was so full of dreadful agony and horrible pain that made me think war, disease and famine were savaging every little corner of the world at all times.

I can totally relate to her feelings as her own family is a complete chaotic mess, and with her son being a horrible toxic piece of constant trouble I would probably have snapped long before her, but it still made me feel very uncomfortable seeing her constantly dreadful look for one an a half hours.

THOUGHTS?