I would give it a little time, see if the dog will come around.
If the dog still insists,
find someone else.
The dog will not turn its back on you, they are loyal forever.

We have an expression back home the goes 'I don't trust a person that doesn't like a dog, but I trust a dog that doesn't like a person'.

For me, it would depend on a couple things. If my dog was regularly socialized with other humans besides me, particularly within my home, and had generally shown a good disposition towards everyone... yet acted like that? It would raise a cautionary flag.

But if I had a dog that didn't get out and about very often, spent most of it's time with only me, and had limited social interaction -- particularly within the house that is it's domain -- I would give both of them some leeway... it's a new scenario for everyone involved, and that can throw a monkey wrench in anyone's day.

Maybe try again, and meet in a neutral location like a park or something, and see if there's a difference in the dog's behavior?

If your dog doesn't have a lot of social interaction other than you at the house, it might just be showing it's protective nature over you and it's domicile, as opposed to there being an issue with that particular person. But if they have regular social interaction and suddenly acted out-of-character with this one particular person, that would seem pretty odd, and raise an eyebrow as to what's up.

My dogs are very important to me. They like everyone they meet (at home, out walking, pet stores, etc.), if they act aggressive towards someone, somethings up.

Has the person got an animal the dog might not like the scent of?

I would absolutely, unequivocally, trust my dog, and give that person the boot, with no remorse.

Is the person afraid of dogs? That's very important to know beforehand. Dogs spend their entire lives reading people and some are reactive to people who show any sort of fear. I've one like this, he's offensive/defensive with fearful-of-him-people, particularly with men.
He was born concerned.

Unless your "sweetest" dog is really a one person animal, or not quite as sweet as you think.
This is a huge issue to me. I don't care if someone has pets themselves but they need to be at least better than "ok" with mine. I won't apologize for this here or anywhere else. Don't like it? TFB

With all that there are dogs who are wired badly, either by genetics, upbringing or both. I've had friends with spooky dogs who were just born that way. They weren't "abused".

Giving up a beloved pet for a "maybe" human is a huge character flaw in my eyes, barring some extreme medical condition/circumstance after years of attachment.

It's already happened to me. I was very interested in a man I met on a dating site. He came over to my house for a movie marathon and it was obvious he hated my dog. So needless to say I dumped him. My dog comes first.

Have your new friend wear a meat suit. Problem solved.

To be serious though... probably just give it time like others have suggested.

I'd trust the dog.

......yep. I'd trust the dog's instincts. I've got a Siberian Husky who likes everyone. So far, she's has only ever taken a dislike to two people who came into my life. She was right on both occasions. They were shitty people.

Idk.
My kids have jokingly said that I love my dog more than I love them.
And my joking answer was it's good that YOU KNOW!?

Reminds me of when my grandaughter found a relationship on line and he came to visit at my daughter's house, where my grandaughter still lived and their cat apparently took to the fellow, so my daughter was certain he was a great person! NOT! When she went to visit him, it was disastrous!

I would give it time. My screen name is the combination of my two dogs. I adore them but they are territorial protectors who need to learn how to adjust. Personally,I’d be patient and give everything a chance to level out. Good luck. And please keep us posted.

my dogs would be fine and if they weren't for the first time ever apart from when an ex-religious friend tried to dominate them then they would have to go due to there character floors. the nice women, not the dogs.

I would try to discover if there might be a definitive source of the dog's agitation, other than dislike of that person...
Yet on the other hand, I wouldn't turn my back on that person either. One dog I had loved everyone, but 2. She might have killed either of those. One of them was about 10, a boy, the other, a stranger walking around this small storefront, like tens of others...

Could your dog, perhaps, be jealous?

First impressions are mostly wrong. Ask your dog to give your friend another chance.

Nothing bacon can't solve.

Did the dog meet the person on neutral territory? I'd try slowly introducing the dog. Start with scent. Let the dog smell that person on you for about a week and then let the dog meet the person at a park or something not where you usually go with the dog. If the dog feels this intruder is in their territory they can be vicious

Trust your canine friend!!!

I've met so many for coffee after some really good chat.....I don't have a dog (love them!) but I have not ever felt a "connection." So many of my friends have met mates online......is there something wrong with ME????

You try to enjoy the time with a fellow human being. But if you fail to do so, you run.

Perhaps your dog was just picking up on your vibes of being a bit nervous about you meeting the person. I know my little mutt is very in tune with my emotions. She's always gets "antsy" when I'm expecting company!!

I love dogs. But honestly, dogs can be wrong and act from a not great place, just as people can. I would not allow another human's judgment to overrule mine so I would not trust my dog more than myself. Sometimes it is just the way a person smells.

I had a Great Pyrenees that hated a friend of mine, who had never done anything wrong to her. But she seriously hated him and we never knew why. She would hear his car coming, long before we did, and would start barking. We worked with her on this, had him sit and give her treats and pet her. It was all good until he stood up and turned to get water from the tap. That is when she bit him on the butt. Fortunately, he had a wallet right there. No warning.