Logically Speaking.. You Can't Support Gay Marriage and Not Support Polygamy

A while ago I heard an interesting conversation happening in a group of people that I walked up to.  It was a lady voicing her displeasure about the "Christian right" and how they oppose (and thereby prevent) gay marriage and how they shouldn't force their beliefs on others that don't believe the same things they do.

After listening to what she said I replied "I am for the legalization of gay marriage" (which I am) "but that means I'm also for the legalization of polygamy."  She did not agree with me.

I asked her to explain why she supported gay marriage.
Her: "No one can tell anyone else who they can love or not love."
Me: "I agree with that.  Now if you extend that logic to polygamy and if you are willing to say the government can't tell a man he can't love another man, why can the government tell a man he cannot love two women, or a woman and also a man, or any other combination?"
Her: "Well I guess, but polygamy, that sometimes involves children"
Me: "Well, obviously, it would be bound by normal laws - only consenting adults. Some gay relationships involve children (sexual predators, priests, etc), which is just as horrible. But that isn't an argument against allowing two consulting men to enter into marriage.
Her: "Ok, well I don't know.  It's just polygamy is... just taboo.  I think it's wrong."
Me: "Ok well that's your opinion.  Many cultures around the world think it's right.  And you're saying you oppose it because it's taboo and you think it's wrong.  That's EXACTLY what you were complaining about the people in this country doing when it comes to gay marriage.  You have to see the hypocrisy in that."
Her: "...      "

So if you believe that  a person can love any other person (consenting adult), you must also support polygamy.
I can only see two counter arguments:
1) Taking issue with it being more than one person - If that logic holds, people should not be allowed to get divorce, or two remarry
2) The counterargument to the above is that it's ok as long as they are not at the same time (consecutive instead of concurrent)  If you abide by this logic and these actions (legalization) are enforceable by law, by making gay marriage legal, you must at the same time criminalize cheating in any relationship, since this is what the person is doing (two people concurrently)

For the Record:
I support both of these simply out of my political philosophy, which could be pretty much summed up as "Live and Let Live."  I could care less what you do, as long as you don't infringe on my or other's rights.  That being said, I believe it is a state issue and the federal government should have no role in it.  I believe in State's Rights.  I know, I know.. that went out of fashion about 150 years ago.

Am I going to go out and protest/campaign to have gay marriage or polygamy legalized?  No.
Why? Because I am neither gay nor a polygamist.  And I simply don't care enough about either issue.

But hey if you care about it either way, please put some thought into it.  Don't say " I'm against gay marriage because God says it's wrong."  Likewise don't say "Well I have a gay friend and he's nice and I think it should be allowed."  Newsflash:  I like money and so do my firends.  That doesn't we should pass a law that gives us free money.

"Ground your argument in thought and logic-no matter what side you're on"