Picture book endings are their own beast, due to the fact that picture books more than any other story are written for repeat reads.
Picture books without a twist at the end aren’t as much fun as those with a surprise ending that moves the story beyond the book.@taralazar
The so-called “open ending” that is gradually gaining more and more acceptance — first in young adult novels and then also in books for younger children — should be viewed as a modification of the linear code (in which a character goes on a journey, changes, then returns home).Maria Nikolajeva
The great challenge of picturebooks — which is also true of other stories but less so — is the need to create a story which stands up to not only being read twice, but 100 times. Much of the re-readability of a picturebook comes from its conclusion.
There is a growing tendency for picture book endings to be left open, and more often than not, they pose questions to which there is no easy answer. Often the themes are what Egoff calls ‘the darker side of human experience’, as if authors wish to insist that the security of childhood be shattered as soon as possible, or maybe inferring that it is fiction anyhow.Clare Scott-Mitchell, Give Them Wings, 1988
THE IDEOLOGY OF PICTUREBOOK ENDINGS
How a narrative resolves, ‘ties up’ or ‘untangles’ (both metaphors are widespread), the complications of story is a recurrent concern among theorists, but is of special interest with children’s fiction. Here, the desire for closure, both in the specific sense of an achieved satisfying ending and in the more general sense of a final order and coherent significance, is characteristically a desire for fixed meanings, and is apparent in the socializing, didactic purposes of much children’s literature. There is an idea that young children require (that is both ‘demand’ and ‘need’) certainties about life rather than indeterminacies or uncertainties or unfixed boundaries. Even a genre such as fantasy, which might be expected to offer a site for a play of meanings and for resistances to fixed meanings, usually shows a strong impulse towards closure. … As readers we learn to look for some sense of completeness, both aesthetic and thematic, over and above the bringing of a series of events to a close. Aesthetic completeness is achieved in children’s literature through representation of symmetries, or movements from states of lack to states of plenitude.Language and Ideology In Children’s Literature by John Stephens
See also Natascha Biebow’s post on picture book endings, with a list of specific things you can do to create a sense of closure. Good if you’re currently stuck!