Yes and No. Your wife can certainly be an authorized user on your credit card account and have a card that goes to your reward account. If you are asking whether she can get the 20,000 sign up bonus then the answer is no. The primary card holder has to be the same as the rewards account holder. Really not a problem with Marriott because spouses can combine points for awards. If you want the bonus, just get your wife to open a rewards account and get a credit card.