My boyfriend (lived together past 7 or 8 years)has told me in the past the way I treat his dog bothers him because it reminds him how his sister treated her children's half sibling different than her bio kids. I spoil my dog and ignore his because I never bonded with his dog, and just don't like him. He's not a terrible dog, just not my type. Hes not smart, and had a dominating, highly aggressive personality towards other dogs. Now that he's older he realizes hes not top dog anymore so he's much less dominating and aggressive, but I can't bring myself to magically love him like mine because he doesn't want to maul other dogs anymore.