And I wonder if it is really her own religious doctrine that is running through the minds of these Muslim chicks who speak Greek prior to the big night, or instead her perception of the religious doctrine of the man she may be targeting. In theory, it is relatively harder to fake vaginal virginity than other forms of virginity. They ain't saving it for the boyfriend who is nailing her in the behind. She is saving it in case the Sheik makes her a hell of an offer to be his bride prior to her tying the knot with the current boyfriend. The anal sex just buys some time in case the Sheik comes through after all. And current boyfriend is not going to say to the a Sheik - hey I used to nail your wife number 5 in the rear - so her little secret is safe and her hymen goes away for the rich guy.
I think this is a marginal thing, if it is ever true. You seem to have a very Holywoodian picture of what Muslim girls are