Respecting the worldview of your partner is very important. In arab countries it can be vital to have the same religion as your partner does. Of course, there are exceptions, and muslim girls sometimes marry christian guys, but in most cases such relationships will be very difficult to establish because of the disapproval from the side of the family and society.
Muslim people value their religious beliefs so much, they might expect their non-muslim partner to convert to islam. It is because religion penetrated all spheres of arab lives and living a day without completing usual rituals is just impossible.