I have two chapters left to write in FMS, my first stand alone book. I've heard writers talk about a sadness they feel when coming to the end of a story. Last night as I looked at the notes for the last two chapters, I understood what they meant.
Not to sound weird, but it's like you prepare yourself to say good-bye to people you care about. I suppose that's a good sign. I hope readers feel the same way when they finish the book.