Marriage isn't just some social construct that can be changed. You can see this through the a bunch of bullshit about the Hebrew language, which is entirely natural and immutable and not invented by people.
"Chewbacca...is a wookie, but he LIVES....on the moon of Endor. WHY...would Chewbacca, an eight-foot-tall wookie, wanna MARRY...a four-foot tall ewok?"