Welcome to Yorkie Talk. My boy Teddy took about a year to fully warm up to my boyfriend -- granted, my boyfriend is a cat person and did a lot of things wrong. The trick for us was to have my boyfriend do most of the feeding and walking.
I would advise your boyfriend to be patient and laid back--not actively engage-- with your doggy when you are not present. Let the dog come to him on his own terms. In other words, have your boyfriend just go about his business and essentially leave the dog alone. Maybe talk in the same room, but not force the dog to be held, play, or do anything. For instance, your boyfriend should walk through the room and say, "Ricky, beautiful weather. I think I'll make some coffee.," and so on --while leaving the dog alone.
My boyfriend's mistake was trying to 'force' interaction on my Teddy and having staring contests, all friendly. I had a tough time convincing him that dogs, especially Yorkies, see that as confrontational and overwhelming.
__________________ Kristin, Max and Teddy  |