I can't but say that during the story we observe the degradation of the protagonist.  Being a kind and careful husband, he turned into a cruel and merciless beast. At the beginning, I really liked a man who seemed to be a positive character e.g.: “my tenderness of heart was even so conspicuous”; “I was especially fond of animals”; “With them I spend most of my time, and never was so happy as when feeding and caressing them”; “my partiality for domestic pets”. But day by day he changed into rude and horrible person of damnable atrocity e.g.: “I grew, day by day, more moody, more irritable, more regardless of the feelings of others.”; “At length, I even offered her personal violence.”.  That's why my attitude toward the main character, totally changed in the end of his narrative.