People watch sport to be entertained and to see who wins and loses. What they dislike is a draw. Readers are the same.
Readers of commercial fiction want to see a winner at the end. Readers of literary fiction are prepared to accept more ambiguity. In either case, the ending must be powerful. Great endings leave the reader satisfied, even if the rest of the book is weak. Weak endings leave the reader disappointed, even if the book was good.
Most of us can write a good beginning. The middle is the most difficult part of a book, but a good ending is essential.
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