You basically said what I told her, except I want to clarify one thing: describing an existing character as a perfect love interest is not a bad thing at all. Of course the two are going to see each other perfect in every way. It's just the nature of it all. Mary Sue-ing is more when you create a new character and make them so perfect in every way...for example, Hatchley could be on the block as a Mary Sue, and that is something to be careful about. But you basically can't fall into the Mary Sue trap with existing Muppets, as they already have flaws, unless you are taking a minor character and giving them a stronger personality. So in other words: the only thing we really need to be careful about with Mary Sues in this story might be Hatchley, but the love interest thing is nothing to be concerned about, as it's only personal opinion of the characters.