If you'd only had the parrot a few weeks, he probably isn't bonded to you yet. And Pajarita is right - in the wild, birds that are companions will only preen each other around the head and neck. The only time they touch each other on the back is when they are mating. I've also heard that stroking under a bird's wings is sexual and should be avoided.
Also, birds in the wild don't have a "hierarchy" like some other wild animals do (lions, elephants, etc). So the cockatoo isn't attacking because he wants to be the boss. He is more likely attacking out of learned aggression or fear.
I don't think you can ever really be on neutral ground with a bird. From what I've read/experienced, a bird either distrusts you because of prey animal instinct/previous bad experiences with people, or it trusts you because you've proven yourself trustworthy. Here is a great post about keeping the whole family on good terms with your bird:
The 60-40 RuleWhile the girl writing the article was a circus performer at the time, I think it can apply to all parrot owners. Parrots are flock creatures; it's not good for only one person in the house to ever be involved with the parrot. In the last paragraph, Jamie says:
If someone is really hated in the house, like your spouse, have them do the good stuff to even out that balance again.
So I would suggest having your partner go through Michael's
Taming Article and do the touch training with your bird. Then they can start to develop trust, but in a hands-off way. If your partner starts out with the bird in the cage, then there is no way for the cockatoo to attack him, so he'll be more confident during training sessions. Also, have your partner feed the meals and and offer treat rewards during training sessions (if you train the bird at all).