I wonder if any of the 'WHY NOT MARRY A TREE, HERPDERP!!' people realize that there are several people in the world who have indeed married inanimate objects (one woman quite famously married the Eiffel Tower)? It's hardly the norm and raises eyebrows wherever it happens, but the point is it HAPPENS.
Yet, the idea of two consenting adults of the same gender getting married is forbidden. I mean, come on...it's..Icky. Unless it's two women, then it's hot.
Wow...that last part was a bit painful to type, but you definitely encounter these people too. The ones who are so adamant that homosexual marriage is against God and that it would lead to our destruction as a society, yet will comment in loud and crude fashions about how hot it is if they see two girls making out in a bar.
Essentially, men can't marry men because that sex is gross. Women kissing and doing things to each other is hot. It's neanderthal-like thinking. They write one off as disgusting and sexualize the other, and hide it behind God.
Behold. The Republican Frat Boy.