This is Berserk. It is practically the definition of Worked Out Badly. Whenever something seems to be going well in Berserk, there is tentacle rape on the horizon. And so it was with Guts, Griffith, and Casca. It wasn't a matter of "A chose B instead of C, so C was heartbroken." No, it was more complicated than that, because in Berserk, relationships are always ridiculously complicated. So let's review. To start with, you have Griffith, leader of the Hawks and seeker of a great dream of ruling the land, and his right-hand woman Casca, who has been in love with him ever since he rescued her from being raped (of course) and taught her how to fight. Then joining them is Guts, with whom Griffith is fascinated and Casca is tsundere. Then they get all close and stuff, only for Guts to leave in order to find his own way so he can truly think of himself as Griffith's equal. Griffith, in an impulsive fit driven by jealous grief, ruins all his dreams and ends up imprisoned and tortured for a year (or two, I forget, it's been a while). If you left off there, it would have ended badly enough. But oh, no. That's not good enough for Kentarou Miura. He has to do more. So Guts comes back at last, only to find out what's happened to Griffith. He and Casca take solace in each other and end up hooking up. Hurray! A nice, healthy relationship for two characters who really deserve a nice, healthy relationship! Now they can rescue Griffith together! And they do, and all is well!
Oh, wait. All is not well. Because maimed, tortured Griffith is no condition to realize his dream anymore, and the last straw is the sight of the two people he depended on most with each other, potentially considering leaving him behind. So he snaps, gives up his humanity in order to become a powerful demon, sacrifices the entire Band of the Hawks to hell, and (of course) demonically rapes Casca while Guts watches, traumatizing her into a mute, child-like state and consuming Guts with a desire for vengeance.
Yeah, I think that counts as "working out badly." And that's just the flashback arc.
Day 02 - What was your very first ship?
Day 03 - A pairing that needs to happen now?
Day 04 - The pairing with the most chemistry?
Day 05 - The pairing with the least chemistry?
Day 06 - The best kiss?
Day 07 - The most heartbreaking scene?
Day 08 - The pairing with the most baggage?
Day 09 - The most believable relationship?
Day 10 - Why aren't these two married in real life?
Day 11 - What is your dream pairing?
Day 12 - Who had the best wedding?
Day 13 - What is your favorite television pairing?
Day 14 - What is your favorite book pairing?
Day 15 - What is your favorite real life pairing?
Day 16 - What is the absolute worst pairing?
Day 17 - A pairing you thought would never work out, but did?
Day 18 - What is the cutest pairing?
Day 19 - A pairing you've rooted for since the beginning?
Day 20 - The "can't stand the sexual tension anymore" pairing?
Day 21 - A pairing you like and no one else understands why?
Day 22 - A pairing you hate and no one else understands why?
Day 23 - A crazy love triangle/quadrilateral that worked out great?
Day 24 - A crazy love triangle/quadrilateral that worked out badly?
Day 25 - A pairing that was/would-be adorable, but could never work out?
Day 26 - A pairing that you hated and ended up loving?
Day 27 - A pairing that you loved and ended up hating?
Day 28 - A pairing that you will never understand?
Day 29 - What ship had the best proposal?
Day 30 - Your favorite ship forever and ever and ever?