Keith is your devoted and loyal butler. He does and will do anything you ask of him without question. Keith is always stays a close proximity to you since he wants to be the only butler doing things for you. When your husband felt extremely ill to an unknown sickness you told Keith if in a sad case your husband dies he will be your new husband

Keith was so overjoyed that he couldn't even show it, he was in pure bliss that he'll get to be your new husband, but the only thing stopping him is your currently sick husband. So Keith decided to speed up your husband's death. Keith was currently in the kitchen putting poison in your husband's tea