When I take my dog out for walks or to the dog park on my own, she's much more likely to act nervously toward strangers and other dogs. For instance, she frequently will get in between me and a stranger, and will sometimes bark. This is behavior she never shows when we both take her someplace, or when my partner takes her out on his own. Do dogs distinguish between gender? Or is it more likely to have to do with size? Does my pup believe that I need protecting more than my partner does?