I'm no canine behavioralist or anything, but using the same theory as I do for any animal...

Why does your BF drag the poor frightened animal out in the first place? If the dog is already afraid enough to hide, I don't see that chasing her around then dragging her to come face to face with what's she's afraid of is going to help any. If anything I would guess that it's making it worse.

That's a tough situation when one person sees the danger but the other one doesn't. I don't envy your situation at all, and I hope you can find a solution to the problem (either with the dog or your BF) before someone gets hurt.

Good luck