The way I see it, we should kick it off like they did (sort of) in the Classical Age. Simply enough, there were three genders of humanity originally: Children of the Sun, Moon and Earth. Sun was two men fused together, Moon was a man and a woman, and Earth was two women. They were all split in halves and now humanity has two genders and different sexualities searching for a suitable "other half".
Now, bisexuals exist, yes, but unless they're also polygamists they need to choose when dating a single person, and many I've met say that they're open to both, but lean to one more than the other. Anyways, not to say that the three-gender origin story is true, but it does encapsulate one key thing people ALWAYS forget: We are different, and that's just fine.
The Gay community has heavily asserted that it should be Gay Marriage and nothing else. I'm from Canada, where it's already legal, but my point in this argument is not "gays shouldn't call it marriage because they don't deserve the term", my point is: "Why do gays want to be the same, when being different but equal is something so much better."
Modern thought seems to revolve around the broken idea that humanity is a singular entity. It's not, it's billions, everyone's different and equal. Being equal and being the same are different as well, and Marriage for so long was defined as "the legal/spiritual joining of a man and a woman", so why change the term? It seems unnecessary, and myself being a straight-leaning bisexual would like to point out that if I did lean the other way, I'd want our own identity for it.