My Secret Unicorn: Snowy Dreams

Lauren's pony, Twilight, turns into a beautiful unicorn when she says the magic words, and together they have some amazing adventures. They really are the best of friends, but now Twilight has a secret that he simply cannot share - not even with Lauren - because it would mean leaving her forever. Twilight has been chosen by the Elders to return to Arcadia to watch over other young unicorns and help them develop their magic.
It's a huge honour, but Twilight can't bear the thought of leaving Lauren. Lauren notices that Twilight is very quiet, and is sure that something is seriously wrong when Twilight's magic powers begin to fail. Finally, after a daring rescue, the Elders decide that Lauren and Twilight make a very special team and that Twilight should stay after all. And Lauren and Twilight promise that they won't keep secrets from each other ever again.