Dogs are meant to be in a pack. They are not a meant to be by themselves. To your dog, you are the leader of the pack, he's looking to you for guidance in what he can and can not do. He will stick close to you for that guidance and the companionship he craves by instinct.
As Colleen Said "Dogs were in a pack before they became domesticated and you are the pack leader and of course she loves you and she feels very at ease when your around and therefore she needs you I say you are lucky to have such a wonderful Dog keep up the good work