“They're not the same thing, but fine, I'll give you several reasons so you'll shut up about it.” (I said we can move on. I’m willing to “shut up about it.”)
“I want a clearly defined meaning for the word marriage, without confusion as to what the genders of the partners are.” (Right. You said you don’t want confusion. I asked you why.)
I want to be able to hear someone say "I'm married" and know that their partner is someone of the opposite gender, and I want to be able to say "I'm married" and convey that my partner is of the opposite gender without having to specify. (Right. You said you don’t want confusion. I asked you why.)
You aren’t answering my question. When I tell people I’m married, if they wonder if I married a man, I don’t care. If they wonder if I married a blond-haired person, I don’t care. If they wonder if I married a 3-eyed monster, I don’t care. I am asking why you do, which you haven’t answered. Again, if you don’t want to, it’s OK. I can move on and you can continue to talk to yourself.