Nidome no Isekai, Shounen Datta Kare wa Toshiue Kishi ni Nari Dekiai Shitekuru

Transported to a mystical realm, Sara saved a boy named Luke from the brink of death. But fate tore them apart, sending her back to her own world. Now, she returns to find the boy she once protected has evolved into the kingdom's most formidable ice magician and a legendary knight. The roles have shifted; the boy is now a man, and his devotion is absolute. A bond forged in tragedy, now ignited by a passionate longing. Witness their reunion in Chapter 1!