My girlfriend had 2 strokes between 2015 and 2016. I have both health proxy and POA. Her only family is brother in PR. Can he take her there?

If he doesn't have legal authority, I don't see how he can.

You raise a good point, that PR is still trying to recover after being devastated by a hurricane. Services still aren't even operating in some areas. It's not an ideal place for someone who needs care.

Does he even have the financial resources to move and care for her out of his own funds?

As healthcare proxy you are responsible for seeing to it she has a suitable place to live. As POA you are responsible for managing her funds in her interest. She is in a care facility and presumably you have arranged for the payment there.

Her brother has no standing to change where she lives or how it is paid for.

Is he in PR now? I'd make sure the nursing home staff knows not to allow your girlfriend leave the premises with anyone without your permission.

Does she have money, maybe in PR. There is something not right here. Why would he want to take her back where things are so bad. Tell the NH that her brother is not to take her out of the facility. That you would llike a call when he comes to visit. Or, ban him altogether.