My experience with health aides for my wife was very positive. One aide, an older woman, went into my wife’s bedroom without an introduction and sat on the edge of my wife’s bed. The aide began telling my wife all about her family as if my wife was her long lost cousin. The aide was so smooth at “disarming” my wife’s resistance that my wife soon joined into the conversation. All awkwardness at meeting someone new was totally avoided.

I was going to suggest exactly what RobertED said worked for him. My mom doesn’t have any paranoia, but I have been careful to avoid any situations that could contribute to her feeling that way. Any aide with dementia experience or training will know that they are a “friend” first. My 20 years as a dementia nurse has come in handy for me. I think you’d be best telling her you have a new friend that you’d like her to meet (the aide) and starting with that. Her new friend can gradually take on more responsibilities for helping her, and your wife will never realize it because she (hopefully) she will enjoy her new friendship and take suggestions for things that involve care as time goes by.
I wish you luck!

RobertED had a great solution. Here’s another idea: When dad need to have his car keys taken away we had his trusted doctor give him the news. He did eyeball me like he sorta knew I might be behind it all, but he gave them up. A trusted doctor can help in many ways. Good luck.

LeePhelps, maybe tell her she is the one that requested the help. Maybe she will take your word for it and agree.