I have asthma and am allergic to dogs. Fortunately, that didn't keep me from getting three
I just increased my daily asthma medication every time we got a dog I would find a dosage that worked for me.
If your fiance doesn't have asthma he could probably try an over the counter medication such as Benadryl. Benadryl has helped me out many times. Good luck. It's not fun to be miserable.