Being hurt inevitably breeds feelings of hatred towards your attacker. But when we hurt others, we have to deal with their hatred for us, and our own feelings of guilt. But knowing what it feels like to be hurt is exactly why we try to be kind to others. That's what makes us human.
You have someone in your life whom you honor and revere so much that every hurt on them is inflicted on you as well. And the closer they are to you, the greater the pain.
The pain of being alone is completely out of this world, isn't it? I don't know why, but I understand your feelings so much, it actually hurts.