Snow Falls Upon the Mortal World, Leaving Only Grief

Clad in white as bright as snow, her eyes cool and clear, she held an immortal flute in her hand. Amid a battlefield strewn with blood and thick with smoke, she stood out all the more.

Their eyes met. His gaze, deep as an ancient well, shifted ever so slightly before returning to normal. Only the hand gripping his sword tightly betrayed his turmoil.

He had saved her twice, yet never realized he loved her. Only after losing her did he understand that he had fallen for her long ago.

A thousand years later, they met again. She had no memories and was engaged to her childhood friend and senior fellow disciple.

Faced with this scene, what was he supposed to do?