Atheist Guy together with Muslim Girl = Clash of the Titans.....who wins?
Try putting it this way:
Person who lives with sensible rules vs person who not only lives with irrational dictates but whose belief systems specifically target her as a second-class citizen.
Sooner or later, the person living in a religious strait jacket will notice that the person she's living with isn't subject to the restrictions that have been foisted on her, that he has greater freedom of action and thought and is probably inviting her to join him in that freedom. I think freedom is one of the most attractive concepts available to humankind, and the only reason why someone might reject it would be because of the severe indoctrination and scare tactics we associate with religion in general and islam in particular. Granted, some people raised with those restrictions act as though they love their chains. I have to believe that having an example of a LACK of those chains up close and personal would make for an interesting education, though.