If she is flying in to visit you (I presume you're both western and non-Muslim), then the hotel people will never know if she's your wife or your girlfriend. Tell them she's your wife, book one room, and enjoy yourselves.

Most westerners don't have their marital status or spouses names listed on their passports (as is common here). You also wouldn't necessarily carry your marriage certificate around with you (again, not common for us), so kind of a "that's my story and I'm sticking to it" strategy.

Good luck!