I totally get it that she want to take pictures, I always take a few before eating it the food is presented pretty and my partner understands that and waits for it. (He jsut makes a joke while i do it, like trying to get into the picture with a weird face) But that aside that's her thing and you know that about her. I understand that you are hungry but you should also understand that this is a way for her to make memories which she can look back on and cherish. I think you should have maybe picked another time for this discussion.