I think that is a fantastic idea, Kyleigh. I have also had success befriending animals using similar methods, including a BLM mustang fresh off the range! Honestly, I think even him reading aloud while she's safe in her crate will help if you guys can't coordinate your schedules to do it together like Kyleigh suggests, or if she gets too worked up when you leave the room.
I don't think it's a time thing, necessarily. I would expect most dogs to bond with whoever spends the most time with them (though not all), but I wouldn't expect one to become fearful. I really think it's that he's done a couple of things that scared her, and since she was already uncomfortable with him and stressed out from moving, it sent her over the edge. I think him spending as much time with her as possible is a good thing, as long as he's willing to do it without putting any pressure on her.
I would actually probably crate her at night for the time being. I know it feels bad to us, but for a dog the crate is a safe and secure place where they can truly relax (if they're trained properly for it, anyway, which it sounds like she is since that's her hiding place). As long as you get her plenty of exercise in the evenings when you're home and let her stretch her legs a lot before you leave for work, she'll be fine and it may actually help her relax to spend a lot of time in her crate. Once she gets a little more settled in and less scared of your boyfriend, you can start leaving her out at night again.
Out of curiosity though, do you guys sleep together (you don't have to answer that publicly of course), and if so, what does she do when he comes to bed? I'm wondering if he's freaking her out when he comes in, so basically every night she's getting a little more reinforcement that he's a scary thing. I've had some problems with fearful foster dogs getting really weird about my ex when we were together because of this exact situation, so that's why I thought of it.
Basically right now, any scary experience she has with your boyfriend, even very small ones that you don't even notice, are just going to reinforce him in her mind as a frightening thing. She'll be like, "Of course he's scary; didn't you see him chase me out of bed?!" "Of course he's scary; he tried to drag me outside to do God knows what with me!" "Of course he's scary; did you see how he was staring
at me?!" etc. That's why it's so important that he totally ignore her and not try to make her do anything. She needs to relax and go, "Oh, the world doesn't end when BF is around; he doesn't even care I'm here!" and then eventually, "Hey wait, is BF seriously giving me a treat? I'm just hanging out here," and then hopefully, "OMG here comes BF I love him and good things always happen when he is here!" It just has to be on her terms.
I know I keep kind of repeating myself here, I'm just concerned from what you said that your boyfriend isn't really getting it (and it is hard, like I said--dogs think very differently from us and it can be hard to get yourself in their mindset) and so giving you ways to think about it.