Dad doesn’t like carer, can relationship with aide turn sour?

iiveii, yes but maybe there's no rational reason for the rift, since his dementia may be driving whatever perception or imagined offense he thinks occurred. You may hire someone else (hopefully a guy) and the same thing may happen after a while or he may be totally resistant to any new help. If his caregiver is female maybe he doesn't want a woman giving him bathroom or shower help. I wouldn't want a guy caregiver for myself, nothing unreasonable about that. There's no right answer in this situation, but just know that your dad's sourness may not be real or fair. Good luck!

iiveii, chances are your Dad may be feeling like he can take care of himself, that he doesn't need anyone around. Sometimes that can happen when a person has Alzheimer's/Dementia [per your profile].

Ask the aide if she is noticing any differences with your Dad's personality.

You may find that whomever you bring in to help Dad, he may not like that person, neither. Best to keep the current Aide since she has already been helping out for the past 3 years.