As long as she's with you and you treat her with class, she will be treated with class commensurate with your Platinum... including sharing your status if you apply for upgrades for the two of you, and (assuming you are on a qualifying international itinerary) access to lounges. It's made easier if you are both flying on the same itinerary (sharing a PNR) and if not, you can usually have them linked.

Have a super holiday!