Life isn't always easy when you're the only repairpony for enchanted devices and conveniences in all of Ponyville. It can get rougher when you're exactly the wrong race for the job...
Sweetie Belle is... special. The kind of special that needs unique care and attention. The kind that creates all sorts of hard-to-solve problems. But Rarity always rises to the task. Because she's her sister. And big sisters fix things.
The book was Twilight Sparkle's greatest creation – ask it any question about how your life might have been and see the answer. It is a work of genius. It is a tempting, insightful, wonderful marvel of magic. It is a terrible mistake.
Twilight was more than willing to keep her life as a nudist private, and deal with the complications as proved necessary. But Rarity would hear absolutely none of it, insisting that the rest of their friends should know about it as well.