Well, I'll be doggoned!

How is the even possible?

That is what is officially known as a warning sign, also called a red flag. RUN!!!!!

I'm sure the threat was a joke, otherwise you are marrying a child. Either way there is nothing wrong with it. Our 12 week old puppy was part of our wedding party, she carried the rings down the isle. My dogs are my kids and part of our family, why shouldn't they be part of the official joining.

So? That sounds adorable. As long as the dog is well behaved.

I heard about this guy who had his grizzly bear that he raised since birth be the best man at his wedding, so a dog isn't so bad if you think about it. I think the bear's name is Brutus. He shouldn't have threatened to leave you over it though. Sorry OP.

You picked a good man. Now you'd better start shopping for a collar with a tie. I've seen them for cats, so they probably exist for dogs too.

just think, if that's how much he loves his dog, how much he loves you

It is hard without knowing the context but it sounds like a pretty extreme response to me. I can't judge, it might well be fair enough if he is so close to his dog. I'm trying to figure out if it would be different if you had said no to his best human friend, but I think even then threatening to break it off over that, when the alternative is spending the rest of your life together, seems harsh to me.

Your fiancee is cute !