...preferably with a happy ever after.

I wanna read about unrequited affections that'll keep me on the edge of my seat emotionally. Whether I feel sad, scared, angry, or happy, I really want to read something that inspires emotions.

But honestly it can just be ones favorite unrequited love story. (tell me why you like it, if it's not too much trouble)

Yaoi, yuri, het, anything goes.

Yorokobi wa Ude no Naka - this is the first one that comes to mind for this request. I just think it is a satisfying story of finally requited love.
Empty Heart - MINASE Masara often used this theme, of one person who loves another person more.
Hydra - the ones who love each other never quite get together (or stay together)

You can also search the tag "Unrequited Love Becomes Requited" and qualify for yaoi (or whatever you like).
Or the tag "Unrequited Love"

Acid Town
Ai wa Doko Itta?
Aiso Tsukashi
Brothers (YAMAMOTO Kotetsuko)
Calorie
Escape (KYUUGOU) - only a oneshot
Gravity Eyes
Ikumen After - sooo cute (it is scanlated though)
Junjou Romantica - gets better in later volumes
Koisuru Boukun - not one of my personal favs, but very popular
Kusatta Kyoushi no Houteishiki
Yume Musubi Koi Musubi
also second Empty Heart.