My husband is a super picky eater. I was able to order a special meal for him at our wedding in 2003. Our reception was at the Boardwalk Inn. We served one of the plated dinners (Shrimp cocktail, ceasar salad, chicken and mashed potatoes). My husband had a cheese sticks for an appetizer and a cheeseburger and potato chips for his meal. We also ordered off the kids menu for my nephew but we asked that he be served the shrimp cocktail since he loves shrimp.
I think that as long as you don't wind up ordering special meals for a bunch of your guests, that they will accomadate your requests. They will definitely accomadate any special requests that you have for you fiance. When I mentioned that my husband would want a different meal, I was told "Absolutely, it is his day too. Why should he have to eat something that he doesn't like" In fact Disney printed a special menu card for him that I had framed!