Before anyone can help, we need some answers to some questions.
Is he only aggressive when there is food present?
What classes have you had him in?
Did you meet his parents? Were they approachable and friendly?
You say he doesn't bite your partner because she halls back - can you explain what you mean by this?
Let me give you a little bit of history on Shiloh, both his parents are police dogs, yes i've met them, didn't act aggressive towards me, but then again, they are adults and both are extensively trained and disciplined. Shiloh is only 6 months old, he doesn't know his own strength, when we play with him, he will try to bite, not sure if this is a form of communication or what, it's not aggressive but we have been correcting him since day one. He left his mom way to early in my opinion, he was only 7 1/2 weeks old. I had to have him get his second shots, my first german shepherd's breeder would not let me see my dog till he had his second shots. Shiloh and his parents and siblings are fed only raw meat ( personally, this to me is edging on a dog to be aggressive ) he hates loud noises, like thunder, car music base, etc... he runs around in circle chasing his tail, this we have been trying to brake since day one. When we told the breeder this, he said there is no such thing as separation anxiety ( this is why Shiloh broke out of his cage twice - when they were closed and destroyed things in the house ) now we have to double lock the gate so he doesn't get out. He's been to training, but your basic sit, stay, socializing with humans and dogs training. My partner is not soft like me, she treats the dog like a dog, I treat the dog like family/pet. She does not cuddle him, or show any true type of affection towards him, she plays with him, but doesn't hug or kiss him like i do. I don't play ruff with him, I am more of a snuggle, hugger person, I'm sure he sense my weakness and takes advantage of it.
" In dog years, I'm dead !"