Personally, I'd tell the boyfriend to kiss my a$$, take the dog to the vet, and do the best you can by the little guy. It could be that he has a lot of life left in him only he's been mistreated.
Our Pomeranian became my oldest's best friend. I mean he would take fingers if anyone attempted to touch her in her bed. You had to call her, not touch her to wake her up.
My first guide dog was the same way with my youngest. If I couldn't find the kid in her crib then toddler bed (usually WITH the dog), I'd find her in the dog's bed complete with her blanket and using the guide dog's belly as her pillow. They were inseparable until the end; the same is true of the Pom we had. These dogs were my girls best friends and are a part of their best memories.
When I was an infant, I was raised with 2 Siamese cats. You know how most people claim cats are dangerous for babies? Well, the only danger about me when I was an infant when it came to these two cats was if someone other than my Grams or my mother came to the bassinet or crib. If anyone other than them came at me, the cats would attack. I have 2 uncles, and 2 aunts who literally HATED those two cats but as far as it came to me, I was snug as a bug and safe from anything because Sissy and Buttons watched over me day and night from everything and everybody until they became so old that nature took it's course and they crossed the Rainbow Bridge just as my former guide dog did and my former Pomeranian did.