Why did the narrator kill his wife in book shawshank redemption?

The narrator in "The Shawshank Redemption" is Red, not the killer. The killer is Andy Dufresne, who is wrongfully convicted of murdering his wife and her lover.

Red never killed anyone. He was convicted of a crime related to gambling and served his sentence at Shawshank Prison, where he met Andy.

It's important to distinguish between the narrator (Red) and the person who committed the crime (Andy). The story revolves around Andy's resilience and determination to prove his innocence, and Red's evolving perspective on life and hope.