#126 - Peach Secret Crush

The very first movie based on a videogame was Super Mario Bros: Peach-Hime Kyushutsu Dai Sakusen. At the end of it, Mario and Luigi rescue Princess Peach, who then leaves alongside her secret better half prince Haru-Oji, leaving Mario heartbroken.

SOURCE: https://www.mariowiki.com/Super_Mario_Bros.:_Peach-hime_Kyushutsu_Dai_Sakusen!