reencounter

Mc has to abruptly leave to protect himself, being the only survivor of his whole orphanage being murdered.
He comes back as an adult planning to find the serial killer but to also find his old highschool friend who always had his faced covered by his disheveled hair.

We see the start and development of their relationship.
Finding out she's just been a pawn to him the whole time she leaves him(via death, but faked). He feels regrets and extreme grief until he goes a little too cucu for coco puffs and decides she's no longer dead and he needs to finds her again to get her back.

Im still waiting for her to leave. But she does do it eventually in the novel.

MC and ML met when they were wee lads and reunite when they're adults but MC is under disguise.
Mc always had the ability to talk to ghost even through being reincarnated.
Using both of these instances, she saves the ML from death multiple times to avoid the known future.

Story starts because of their reunitement.
ML left out of nowhere as a kid leaving MC alone and wondering wat happened with a plan to return only when he's rich.
However this turns south, when MC gets into an accident and "dies" but reincarnates into another body. ML is immediately is suspicious and believes somehow MC reincarnated, following him around until he gets MC to admit it.

"hidden identity" element through reincarnation
One relationship with an enemy in her old life but finance in her new.
Then another relationship with who she considered her greatest ally in her old life but now a dirty traitor in her new.

We see their relationship at it's worst. MC tries to kill herself but instead she wakes up in the body of her husband. They uncover the past resolving the present issues, but ultimately MC divorces him and leaves. They reunite after a decent amount of time apart, ML begging for her to come back.

MC knows her father plans to kill the heir to a rival family because she's a reincarnate. She takes the heir for herself as a "plaything" while really protecting him from her family. She pretends to follow her father so she can set the pieces in place to take revenge on him when the time is right. Later she reunites/"meets for the first time", the heir from years ago.