Insanity 
Rick’s transformation from the good guy to a survivor ends up in him overcompensating. Where he wanted to give second chances, he kills people instantly. Where he wanted to forgive his wife, he shuts her off completely. He isn’t happy, he isn’t better off, he just doesn’t know how to cope. Things get even worse when Lori dies. The guilt, combined with that of killing Shane drives him towards hallucinations and insanity. It takes him a long while to come back to his senses and find middle ground.
