I wrote this story for Flutterpriest's birthday.
 
"See you tomorrow Princess."
>"Anon, how many times do I have to tell you? Call me Cadance."
"Y-Yeah, sorry. See you tomorrow Cadance."
>She gives you a cheery smile and takes off into the sky, calling back to you as she soars to Canterlot.
>"I'll look forward to it!"
>You wave goodbye to her before unlocking the door to your house.
>Once the door is unlocked, you push it open.
>The entire house is pitch black.
>Walking inside, you close the door behind you and reach for the light switch.
"Why did they put this thing so far from the-There it is."
>You flip the light switch up and fill the room with light.
>A pink card sits on the table.
"Huh?"
>When you walk over and pick it up, you look both ways to see if anyone is in the house with you.
>No one is.
>You look down at the card.
>It's got a little bit of glitter in the shape of a heart on the front of it.
>Opening it reveals a picture of you and Cadance when you were sitting on a bench in the park earlier today.
>But Cadance's head is scratched off.
>Underneath the picture are the words, "Why her?"
>A thump noise comes from upstairs.
>Placing the card back down on the table, you walk over to the stairs.
>Each step up seems terribly loud and you hope whoever is in your house cannot hear you.
>You reach the top of the stairs and go to the bedroom door.
>Grabbing the doorknob, you twist it and push.
>The door slowly opens and you see Fluttershy sitting on the bed.
>Oh no.
"U-Uh, hey Fluttershy! What are you doing here?"
>She gives you a bright smile.
>"Oh, I just came to check on my favorite person in Ponyville~"
"Haha, well that's nice of you. I'm doing great."
>"That's good."
>She starts tracing circles on the covers with her hoof.
>"What did you do today?"
"I uh, not much really. Just went to work like any other day."
>She stops talking completely and stares at you.
"L-Listen though, I need to get some sleep and-"
>"Why?"
"Because I need to do some things tomorrow-"
>"Why do you lie to me?"
"...what?"
>She stands up on her hooves and her stare becomes blank.
>"Why?"
"I'm not lying to-"
>She stomps her hooves on the bed.
>"YOU'RE LYING."
>You stand there shocked.
>"You went on a date with that pretty pink princess."
>Shit.
>"Skipped work, met her at the train station, went to the fair, relaxed at the park, and watched the sunset."
"How do you..."
>"But you don't understand. She just wants to hurt us. She wants to take us away from each other."
>You back up a little bit.
"Fluttershy, that doesn't make any sense. We aren't together."
>"I know you and her aren't together. And I made sure she stays away."
>She smiles.
>"Forever."
>You take another step back.
>She can't really have done that, could she?
>"Anon? Where are you going?"
"T-To um, the bathroom!"
>You turn to the left and sprint to the stairs.
>A hoof grabs your ankle and you tumble, slamming face first onto the hardwood floor at the bottom.
"FUCK!"
>A jolt of pain shoots through your body when you try to move.
>Your leg is twisted around at the knee.
>You could play patty cake with your heel.
>Fluttershy grabs your hands and turns you around, dragging you back up the stairs.
>"The bathroom is to the right, silly."
>She drags you up the stairs, each stair making your damaged leg slam down.
"AH! B-Be careful!"
>"It's okay honey. I'm here."
>Eventually she makes it up them and pulls you to the bathroom.
>Closing the door behind herself, she takes off your pants and boxers with her teeth.
"F-Fluttershy... This hurts so-"
>She pulls them over your broken leg.
"MUCH!"
>She stares at it for a few seconds with absolutely no emotion.
>Then she lifts you onto the toilet.
>"You can go to the bathroom now."
>She steps on your foot, making you scream out in agony.
>"Unless you were lying to me again."
>She stops crushing your foot and you do as told.
>The noise of piss hitting the water makes her smile.
>"Good boy..."
>She scoots closer to you, resting her head on your leg.
>Inhaling deeply, she lightly traces a hoof up your good leg to your crotch.
>You place your hand there to block it.
>She looks up at you.
>"Move your hand please."
"No."
>She pushes a hoof down on your knee and you hunch forward.
>"I said please."
>You remove your hand.
>She leans closer to your crotch as you relieve yourself.
>She keeps her hoof on your knee to keep you still and pushes her muzzle between your legs.
>Her tongue wraps around your dick as you piss and tilts it into her mouth.
>This mare is fucking insane.
>She lets out moaning sounds and pushes down lightly on your leg.
>You grab her mane and she stops pressing down.
>A few more seconds go by and you finish peeing.
>She pulls her head up and licks her lips.
>"I've always wondered what that tasted like... Now come on, let's get you back to bed."
>Afraid she'll hit your leg again, you allow her to carry you into the bedroom.
>Once you enter it, a smell that wasn't there before now fills the room.
>It's got a hint of copper in it.
>Fluttershy helps you onto the bed and your leg bumps into something already there.
>The thing moves and tries to speak.
>You grab the sheets and pull them off to reveal-
"Cadance?!"
>She looks around for your voice because she has two deep red pools where she once had eyes.
>"I saw the way she was looking at you... Now she won't be able to anymore."
"FLUTTERSHY, STOP THIS!"
>You turn to see her holding a brick above your broken leg.
>"No. You don't want to help her. She's the reason our relationship is broken sweetie."
"But-"
>"Just push her off the bed. Then we can get some rest."
>You do nothing.
"Please don't make me do it."
>She smiles and drops the brick down on your leg, making you cry out in pain once again.
>"It's okay honey. I'll do it for you."
>She flies over and bucks Cadance off the side of the bed.
>Cadance lets out a shriek that is silenced immediately.
"W-What..."
>You lean forward and pull the brick off your leg.
>Fluttershy looks off the side of the bed with a smile on her face.
>You crawl over and peer off as well.
>Cadance lays there, her entire body pierced straight through by hundreds of long shards of glass.
>Fluttershy turns to you.
>"Now we can get some rest!"
"C-Cadance..."
>You try to grab out at Fluttershy, but she is too fast for you.
>She flies to the foot of the bed and stares at you.
"WHY WOULD YOU DO THIS?!"
>"Because I love you honey."
>She grabs your broken leg and you whimper as she ties it down to the wood on the bed.
>You try to kick out at her when she grabs your other leg, but you miss.
>She wrestles with your leg and eventually ties it down.
>You sit up and swing at her when she nears your upper body.
>She dodges the blow and grabs your right arm.
>As she drags it to where she wants to tie it, you repeatedly punch her in the side.
>Fighting through all the pain, she still manages to tie your arm down.
>When she goes for your last remaining limb, you wait until she gets close to swing.
>You hit her square in the torso.
>Instead of flying away like you expected her to do, she clings to your arm and takes it to the other corner of the bed.
>Once she ties it in place, you glare at her.
>"Don't worry honey, I didn't forget."
>She flies out of the room and down the stairs.
>This can't be good.
>Slow and loud hoof steps are heard coming up the stairs.
>Fluttershy enters the room carrying something on a plate.
>She hums a tune as she walks over.
http://vocaroo.com/i/s0MrcxfEzOj7
>She gently flies up and places the cake on your chest.
>"Happy birthday."
>She then walks back over to the door and smiles in on you.
>"See you in the morning."
>The door closes.