I’ve been in a situation where I did have to give power of attorney to my then (long term) boyfriend because I was very very critically sick. The laws around POA are very strict in the sense that even if you did sign it over it wouldn’t be honored if you were competent to make your own choices. POA also expired pretty quickly when a person is conscious, like if you’re in a coma long term or something the POA will just by default be honored but beyond that it has very little power, it’s constantly reassessed and even if it is signed over while you are competent judges will consider it moot and allow the competent person to exercise their own rights. If he does want this he clearly doesn’t understand what for or when the law considers it appropriate, even if she did sign it over to him it wouldn’t make any difference, it wouldn’t be honored.