To her, your voice is your voice not someone else's voice.
If you share a Youtube account with your wife, "someone else" means someone other than you or your wife.
The more interesting and troubling point is your use of "synthetic you" to make the real you sound better!
The ethical challenge in my opinion, is that your status as living human narrator on a video is now irrelevant, when you're replaced by voice cloning. Perhaps we'll see a new book by "George Orwell" soon. We don't need the real man, his clone will do.
Why?
I presume you wouldn't do that? How about replacing your own voice on a video that you make, allowing your viewers to believe it's your natural voice? Are you comfortable with that deception?
Everyone has evolving opinions about this subject. For me, I don't want to converse with stand-in replacements for living people.