My Childhood Friend, a Prince, Won't Stop Clinging to Me

When he was young, Erik, the Fifth Prince, used to visit Marilee's family quite often, until one day when he stopped coming. Five years later, Marilee enrolls in the Royal Academy and finds herself reunited with Erik, a standout student there. Even though she doesn’t want anything to do with Erik anymore, he keeps pestering her for some reason!?

(Source: Square Enix, translated)