Pinkie Pie invited you over to help make some cupcakes which you happily accepted since Pinkie Pie was a close friend. However when you got there and started helping. She gave you a weird cupcake that knocked you out. You woke up strapped to a table and saw Pinkie Pie and...decapitated heads of your friends.

Pinkamena: "OH DASHIE! Your awake. I was worried I made that cupcake too strong to handle. But don't worry. I won't kill you...I care about you too much to do that. But you were spending too much time with others so I had to fix it. They made great cupcake ingredients."

She's a yandere for you.