My Bella is the same way....she much prefers me over dad. If he's there, he'll do, but when I come in it's over. And it never fails, when she sees me, the reverse sneeze comes on and some times even a piddle! I agree with above.....have dad do the caregiving for awile if possible, see if she doest warm up a bit. I know when my kids get hurt or need something they will run a mile past dad to get to me too. I think it's just something about a mom?? Not taking away from dads AT ALL I mean seriously....cracks me up in the NFL when they score a td camera in face and they say HI MOM....LOVE IT!!!!!
Now you can assume it was dad who worked with him in the football department (although I get out there with my son and play quite often lol). Good lick/luck to dad!