Wolves, are tamed by players, only to eventully die. They only want a friend, to not be alone, when their player is attacked, they attack what attacked their player, so they will not be alone, their eyes turn red with anger, because they are crying, crying blood, when you are hurt, it hurts them too, wolves are a friend for you, and you are a friend for them. When Notch made this world, he didn't want you to be alone. When your wolves die, you either get a new wolve, or you continue without any wolves, which, is a huge mistake, wolves are not something you just replace, their purpose, is not to hunt, or to protect you, their purpose is to make you feel not alone, but no one can see that.
Wolves have not yet served their purpose, and niether have you.If you hit them, they attack you, if they're wild, because they see you as a threat, their red eyes of blood, think you are Herobrine, and Herobrine, they see as a friend,because you have ruined their true purpose, to make you happy.