Waga Itoshi no Kyuutei Majutsushi

Through an accidental mishap, the dashing royal knight Leonhardt falls under a powerful charm spell cast by the renowned court magician, Eurys. As they spend time together to break the spell, Leonhardt's initial lust fades, replaced by genuine affection for Eurys’s hidden, tender sides. Even after Eurys declares the magic is gone, Leonhardt’s feelings remain, but his confession is met with rejection, and Eurys announces his departure from the kingdom.

(Source: Kadokawa, translated)

Note: Includes two extra chapters.