In the Black Cat, Poe uses the first person point of view to narrate the story. By doing this, Poe lets us know exactly how the main character is feeling and why he performs certain actions. The reader is given all details from the perspective of the character, which does not mean that it is an objective point of view. In fact, in this story, Poe describes the personality of the main character through his actions and thoughts.
By telling the story form this point of view, we can only infer the personality, feeling and emotions of the rest of the characters, in this case his wife, as the main character does no describe her in detail. The only reference to his wife's personality is that she likes pets too. The focus in the story is the main character's head and what he thinks.