...seems that the first commentator does not have an idea of Japanese cinema or even the construction of a movie. Sorry for the harsh words, but do not know why you decide to comment about movies, if you do not discern even the story line...
-One of the things that the director is showing is the fact that communication is everything in a relationship so if you cannot stand some situations for one reason or another, would be very difficult to carry on with a successful marriage.
The point of views are based on four examples of a marriage in the different stages of life.
The strange behavior of the main wife is based on what she found as a fortress to manage the death of her Mother when she was a child and to bring some better moments to her Father in those difficult days. Kind of a refuge constructed on great Literature of the XIX century.
All these relationships are between people that tried hard to keep on going but at some point is not up to you only; may be the destiny and dead is working against one of the parts involved too.
The firsts half an hour is somewhat bland then the rest grows slowly but consistent so if you pass that and dive around some subtleties you would finish with something that provides hope.
No doubt that all we need another person at our sides but many times this is not available for any body or is a harsh road.
We as human beings struggle all our life with some type of relation, losing the energy, stressing out us then we are dead...is evident that we do not like to live alone all our life.