I think this is mostly a boyfriend problem, because he's not disciplining his dog. My guess is the dog is testing boundaries and misbehaving with you because you're new and taking away your boyfriend's attention and affection that used to be directed solely at the dog. You can try making friends with the dog, by taking it on walks and playing with it, and by giving it boundaries and discipline. Stop it when it destroys your belongings, and make your boyfriend pay for their replacements. If the dog nips at you, or pulls the blankets off you, or takes your food, correct the behavior. If you're not sure of the best way to do this, consider taking an obedience class with the dog. Training sessions can be a good way to bond and also make sure the dog respects you. If your boyfriend is not supportive of your efforts, or consistently undermines them, its a pretty good sign he's valuing a misbehaving dog over your relationship and it is probably time for you to move on.