No, you didn't explain it.  You just stated it as if were fact with no backing.  In most cases bestiality is illegal because it's considered animal abuse.  Why would we stop thinking this because homosexuals are getting married?

Oh, and btw, bestiality is still legal in 13 states of the US.  Homosexual marraige is legal in 6...

I'm pretty sure that if the animal didn't want it they would make it pretty damn clear, assuming it's a large animal like a dog or a horse (which is the most common I would assume).

You must agree then that interacial marriage was also a step towards beastialty, correct?

who cares if it is? We need someone to shag sheep, don't we?

slippery slope logical fallacy. 

That's a good argument. And as you said, paraphilia is in the eyes of the beholder. Each man his own judge, I personally define paraphilia as anything outside the union of a man and a woman of consentual age, no matter the race or culture, not directly related (aka siblings). Anything outside of that I personally consider, by my conscience, to be paraphilia. However, no matter how one delimits the bounds of paraphilia, accepting one form is a means to accepting another, in other words my logic stands, we just start from different premices.

A 12 year old girl might not make it clear either, but that doesn't make it any less illegal.  Minors aren't legally qualified to give consent, and neither are animals. 

Again, why would letting two humans who are of sound mind, of the same species, and are capable of giving verbal consent, lead to people suddenly thinking that animals are capable of entering into consensual sexual relationships?  Please, explain to me clearly and in detail how one thing leads to another.

The reason why a girl would not make it clear and a horse wouldn't (horse as the most efficient example for my side of the debate), is that a girl would stay quiet for much more complex reasons, and so it's hard to tell what's going on in her mind, same could be said about a 12 year old boy. But an animal staying quiet is less likely due to some kind of psychological pressure they would feel.

Example, parental sexual abuse. The child would likely not say anything so as to not alarm other members of the family, or because the person committing the abuse is a figure of authority.

And what is that definition based off of? 

Looking at the definition of paraphilia, it deals with sexual attraction which isn't normal. And in the past, interacial marriage was certainly not normal, it was even illegal in many areas. So, interacial marriage was definitely a form of paraphila. Therefore, you must agree that, at the time, the legalization of interacial marriage was a step towards any other form of paraphilia. Correct?

As was consensual, non-arranged marriages before that.