Another other story idea

My friend told me I should write my own Fimfic, but I don't have the magic for that :/
So I'll just do what I've been doing! that is:

Someone has a huge crush on another for years, then discovers that s/he has a life-threatening disease and s/he by their friend(s) to ask her out. She tells their best friend "If I was ever selfless, forgive me this once for being selfish." They finally manage to go out with their dream-come-true special someone and have the greatest time, but s/he lays on her deathbed the next day, and passes away the day after that. The narration switches to the other character as they reflect on their past with their now-dead friend a week later.

If pony: mane character is Twilight Sparkle. The story starts with her in Sugarcube Corner while Pinkie is away and its moderately busy. She reflects on how she got to know Rainbow Dash by looking back at their memories that they had gathered throughout the years. Twilight's horn is decaying, which is life-threatening because when her horn falls apart her soul will be detached from the leylines which, in turn, causes her spirit to dissolve. Her body dies quickly afterward. Twilight admires the athletic pony's incredible skill and grace in everything she does, even when she messes up its still flawless in her eyes, but she is afraid to ask her out because she knows that Rainbow doesn't want a relationship. She has tried before, being shot down both times. The first time was an innocent and shy request to dance with her, and the second was a blunt "will you go out with me?" which is replied to with a "I love you like a sister." Twilight tries desperately to dampen her crush and forget about it, but there is something inexplicably AMAZING about Rainbow Dash that she can never figure out, and drives her feelings crazy whenever she's around her no matter how hard she tries to dampen the feelings. It wasn't 'love at first sight,' but rather an almost gradual thing for her that quickly snowballed and lasted for years. She sees the way Dash is around other people, both friends and strangers, and just falls for her harder. It wasn't for a while after that they became friends...

and so on. :D I hope someone skillful comes along and makes this idea that came to me during Algebra II a great piece