I think you just have to let him be her dog and after you get more relaxed about the whole situation your puppy will warm up to you too. That happened in my family. Even though Tom is "all my baby" but he warmed up to my husband and he knows his place in out family is after my hubby unfortunately right along with my daughter
He thinks he is even with her). Your gf should also help to establish the order. I do not think that Tom will ever be totally cuddly with my husband (it's almost 100% male yorkie thing) but they sure have a great time together. We plan to get a female yorkie pretty soon.