[Wabbit]

Since your little guy is a rescue...you have NO idea what he's gone thru before you got him.... or what abuse he may have suffered....soooooo you will need to help your fiance to understand how actions like his only makes your baby more fearful and distrustful of him. AND
Your fiance reaching out and grabbing him up while he was in a fearful state only contributed to his getting bit.

He will need reassurance that your fiance doesn't mean him any harm....and your fiance will have to learn that "man-handling" (i'm not saying he was hurting him) a fearful little guy will only escalate his terror!!!

I FIRMLY believe in CESAR MILAN...but nowhere does he say you are to DOMINATE an already fearful dog!!!! I didn't catch how long you have had him...but it's just going to take time for him to learn to trust.....and hopefully your fiance will not do things like that in the future...because it will not help to balance your little guy out. He needs love...understanding and PATIENCE....if he's ever going to get out of that state. Good luck...