I am a Reform Jew and ill-equipped to answer this question from a close friend who is not Jewish. Apparently, my (non-Jewish) friend is NOT invited to the (Orthodox) wedding of the daughter of a close friend & co-worker. It was explained to my friend that Orthodox Jews simply don't allow or invite non-Jews to their weddings. I told my friend, whose feelings were genuinely hurt, that I had never heard that tradition. As far as I know, anyone can invite anyone they want to their wedding. But, to repeat, I was raised Reform and am no expert on Orthodox traditions. You are the experts, right?
It is difficult to rigorously prove the negative, but as someone who has much familiarity with Orthodox Jews and Orthodox weddings, I can state that there is no such prohibition. Non-Jews at Orthodox weddings are not so rare (although admittedly not overly common).