My yorkie is like my shadow, and he's very much a mommy's boy, but he plays alot with my husband too. I'm home all day with him, then I go to work in the eve., and my husband is home with him. So, he's used to both of us being his caregivers. Try having your boyfriend give him a bath or let him do some of the feedings, brushings, etc. As much as some of them hate baths and brushing, it's still a form of bonding. If you both share in the responsibilities of taking care of him, he will soon learn that daddy can be pretty fun to play with too.
Having said that, he will only snuggle up with mommy at night lol. Good luck to you!