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.

or it loves your smell. 

I also agree with Colleen - he may also love you and want to be your friend - you could get another dog to keep him company especially if you are not around so much.

He looks up to you,the poor little bastard.He doesn't know any better.HAHAHA!

To him you are the Alpha male.

I am with Colleen  once again    she very smart  woman   

I had a Lab that would get in my lap when he was fully grown and whine like a puppy whenever his food dish on the porch was being eaten by a bear.

  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

my last dog(also German Shepherd) was like that ,couldnt  even have a bath without her coming in the bathroom

my last dog(also GSD)was like that,couldnt even have a bath without her being in the bathroom.At least my present dog will wait at the top of the stairs!!

Because he ♥ you.

Trust me, he'd rather be with a bitch.

" For companionship."