I know puppy biting is normal, but Raika bites me excessively (in play) but doesn't bite my boyfriend. My arm is all scarred up from her little needle teeth. I don't understand why she likes the taste of my arm but doesn't seem to have the urge to bite him (not that I want her to). When she does it I scold her and say "NO BITES" very firmly. That didn't work very well, so I tried yelping and turning away from her like she's really hurt me. That worked for a while, but now she thinks it's a game. Any advice?