Well, it's simple: All the heroes had participated in the rescue, but you struck the blow against Darktoon and freed her. Now this Mommy of the Sea is deeply in love with you; you're her hero, and she can spend time with you now that Moody Clouds has been destroyed.

Inspired in this animation: https://youtu.be/mvGN5JtNEgw?si=C_g0qhMYgmKoJYoH