To add to what queer said, the only “natural” form of relation between a man and a woman is polygyny, where the biggest and strongest males monopolize all the females. Marriage as we know it came about as a way to reduce competition between men and to ensure the inheritance of property. There’s nothing “natural” about monogamy either.
Same sex unions have existed in ancient Greece, Rome, China, Fiji, and even among Native Americans. They all predate Islam. Your only argument is “because I say so”. Don’t even bother replying, we’re done here.