Aww I'd probably feel the same way as you if my baby gravitated towards my BF! I got my puppy 2 weeks ago (he was a present from my BF) and although we spend around the same amount of time with Oliver, he is COMPLETELY attached to me...it happened within a few days of getting him. I do everything though, take him out to pee, feed him, play with him, etc. The best bonding thing I can tell you is to get some of his food (or Cheerios which my pup loves) and spend 45 min to an hour just sitting down with him teaching him to sit, lay down, etc. and give him his rewards. My Oliver LOVES to do that and its helped us bond soo much. I do it during his dinner time because not only does it ensure that he is eating enough but he thinks its playtime too and loves it
Best of luck to you!!