I think you should explain to you BF, that all Yorkies wear topknots & most even wear bows. Maybe have him watch a Dog Show.
As for grooming, please hide all of the scissors from him!!!
Take your puppy to a professional groomer, and let your BF see the difference between "chopping" up your puppy's coat, compared to a professional groomers work.
My DH has never even thought to trim either of our girls, and they are both in full coat.
Good Luck!
Sheila