Celestia is tired of ruling Equestria. So she decides to take a day off... using any means possible.
In this case it involves pretending to be sick and tricking her sister into ruling in her stead for the day.
Well, her clever plan succeeds, and Celestia is left to herself all day long. As she is enjoying her time off, she discovers a stack of letters in her bedroom; letters that she hasn't thought about in a very long time.
Letters from Rainbow Dash.
Celestia begins to read these letters from so many years ago. They are full of Rainbow's passions, her hopes, her dreams, and her love - her love for one of her best friends: Applejack. They follow Rainbow's relationship with Applejack, blossoming from friendship into something more, resulting in cuddles and kisses and eventually in Rainbow Dash learning some of the most important lessons that anypony can ever learn.
The last letter from Rainbow had been an invitation to a wedding. And it had been sent a year ago.
So why had Rainbow Dash stopped writing?

Applejack promises to spend some time with Rainbow Dash, and naturally the pegasus asks to share some naptime with her in one of the apple trees. Applejack agrees, and even finds herself having fun... until her big brother turns up, as big brothers have a habit of doing, to catch her in a rather compromising position.

Note: not my cover art. https://www.derpibooru.org/380712
Another note: some of you may recognize this as a chapter from one of my other stories. I decided to post it as a stand--alone story as well, because I originally wrote it as a short stand-alone story and just posted it as a chapter on a whim. What you are reading now is how it should have been posted in the first place. (Besides, you can never have enough AppleDash.)

When Twilight Sparkle accidentally casts a spell on Applejack that forces her to voice all of her thoughts, Applejack realizes that she is in danger of revealing her feelings for Rainbow Dash to the entire world. At least Rainbow Dash isn't around to hear her.

Right?

Cover art by the amazing and talented Multiversecruise!!! Love this dude!!!
Entry for the Appledash contest.

Featured on August 24, 2017!

Applejack and Rainbow Dash are Canterlot High's most athletic, most competitive, and most stubborn students.
They're also the most oblivious.
Rainbow Dash is head-over-heels in love with her best friend, Applejack. Applejack has one hell of a crush on Rainbow Dash. And, naturally, neither one of them knows how the other feels.
Who knew saying 'I love you' could be so hard?
But they'll manage it in the end. And when they do, they'll go on to tackle the rest of the school year hand-in-hand, side by side. They'll laugh and cry; they'll be hurt and be healed; they'll live their life to the fullest with their best friends and encounter all sorts of surprises. They won't realize it, but their experiences - their love, their kisses, even their stupid competitions - will be documented by Pinkie Pie with her trusty camera, trying to immortalize the slow and sweet and sometimes stormy romance of her best friends.
And when she shows them her album at the end of the year, when they prepare to step out into the big wide world, Applejack and Rainbow will realize that, well...
It truly was their year.

Link to cover artist's page:
http://ranbluesue.lofter.com/post/39ebde_cf8e4b1

Rainbow Dash and Applejack have been having interesting encounters over the last couple of weeks, but now Rainbow is wondering where it's going. Little does she know, she's about to be surprised.

Five times Rainbow Dash kissed Applejack, and the one time Applejack took the initiative instead.

The first time it was by mistake. The second time was by choice. The third time was by habit. The forth and the fifth time... it doesn't say. But for Rainbow Dash and Applejack, it becomes a pattern...