Although you haven't given me much to work with, I would suggest that your dog is favouring your partner because he does not get the attention he wants from him whereas you already give him that same attention. In a pack you have the 'top dogs' as drgnrdr puts it. The alpha female will primarily concentrate her efforts on keeping the females in order (the lower ranking males have no desire to usurp her breeding position, only that of the alpha male - they are heterosexual after all) and the alpha male will concentrate on keeping the lower ranking males subordinate. In this way I would suggest that the puppy, being male, is confused as to his rank with reference to your partner (the alpha male). In short do as drgnrdr suggests and have your partner get more involved with the puppy. Also don't worry if it's your partner who's getting all the attention, this doesn't necessarily mean the dog favours him.
Alternatively it may well be a much simpler problem. Try modifying the way you talk to the puppy, it could be simply that you aren't using an appropriate tone of voice. If it is a matter of calling the puppy a tone which eminates authority and meaning will almost always be obeyed over the cute and cuddly voice which essentially says 'come over here if you feel like it'. Just play around and experiment with training technique until it works well, then ensure a sense of consistency.
Finally some of what drgnrdr says confuses me somewhat. In my experience with wolves and to a lesser extent with the domestic dog I have always found that the males provide much more of a paternal investment than would be suggested above. Especially in wolves the alpha female will almost always hand over care of pups to other members of the pack once they have been weaned, a kind of babysitting scheme. There is no evidence I have come across to suggest that the alpha male has any less involvement in dogs.