@zz2000 the main character's ex gets fucked up, in part because his hobby is detonating every bridge he has. It ends with him (Minho)
begging his ex to take him back, "apologizing" while still clearly thinking he did nothing wrong and ignoring her repeated rejections. She finally makes him understand she's rejecting him by having him do one last bdsm scene. Literal cuckholding. He expected humiliation, but not being forced to watch his ex fuck someone else.
That's not the end though, the actual end is that since he's now at rock-bottom with no way out,
he goes crawling back to the man who orchestrated his destruction (Wookyung), somehow thinking that despite his intense homophobia, some "gross [gay] freak obsessed with him" will at least help him get back on his feet. Nope! Yandere end. "Unhappiness suits you the most. Please be unhappy with me forever."
I'm sure everyone won't agree with me. But it was the best end. Perfection. There is no one I will kin as hard as Wookyung. I love my evil Machiavellian king.
Don't worry though, that kind of harsh, painful end is reserved for Byun Minho. HIGHLY unlikely we'll see anything like that here. The worst Gyerin gets is that she wants to be more than fuck-buddies with the original MC and she's really sad when that doesn't happen.
Everyone wants Gyerin to be happy lol that's why she gets a side story with an entirely new character
