Sorry to hear all this but am I reading correctly in that you had your dogs before the BF? I guess I'm old school her so forgive me if I sound a little harsh - don't want to be - but I've dated a lot of guys in my life and I know I am an animal lover and always will be - if any of them did not like my animals then as much as I liked, loved them then out they went. My motto was love me, love my animals..lol. I guess I'm confused..if you got your doggies before the BF didn't you know about his allergies when you met him and talk about this from the get-go?
I wish I could help you with a solution but you two need to work this out soon before you get married and so sorry that you have to decide between your babies and your BF.