Ashes to the Stars: A YA Dark Romantasy (Rewritten Fates Book 2) by Arden Fang

They broke fate to be together. Now fate wants its revenge. Ellas Valentin tore the world apart for love. She shattered her destiny and plunged the kingdom into eternal night—all to save the boy who died for her across lifetimes. But Noct doesn't remember her. Reincarnated without his memories, he's building a new life with someone else. And while the golden thread of their bond pulls Ellas toward him through a starving, monster-twisted world, she doesn't know if the boy she finds will be the one she lost—or a stranger wearing his face. As the eternal night fuels a rising army of nightmares, Ellas must confront the truth she's been running from: to save the world she fractured, she may have to destroy the one soul she was never meant to lose. For readers who crave love that defies lifetimes and a darkness that dares it to survive.