brit and tallg.. may be they met in Qatar, and then they got married in their country , let's say during their vacation time, and came back to qatar married. maybe their mistake is that they didn't authorize their marriage by stamping in the relevant Ministry in Qatar..
I don't believe that muslim woman cannot married christian man. I think it was some issue with the formalities.

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“You become responsible forever for what you have tamed”. Antoine de Saint-Exupéry