Yes, you can make a points booking for someone else, including your wife. If you want to do it by the book, you should notify Marriott in advance that the other room will be in your wife's name (and add her Bonvoy number). Obviously her Platinum benefits will apply. The changes in the Bonvoy T&C allow only 5 such gifted award stays per calendar year.

You can also try just booking 2 rooms in your name and adding her Bonvoy number once you arrive in the hotel.

Or you can transfer max 100k points per year to her account and book from there.