Princess Luna was banished to the moon for a thousand years by her own sister. During her exile, her mental and emotional state continued to deteriorate, and for centuries her own kingdom perceived her as a monster.
Stanford Pines was trapped in another dimension for thirty years due to a reckless fight with his brother. While his brother spent decades trying to get him back, the rest of the world never even realized he was gone.
Queen Eclipsa Butterfly was falsely imprisoned within a crystal for over three hundred years, had her infant daughter stolen from her, and could do nothing to prevent her child from growing up in an abusive and hateful environment all due to her race.
Princess Elena spent forty-one years trapped inside the Amulet of Avalor, and was helpless to stop a monstrous tyrant from murdering her parents and usurping the throne.
Della Duck was stranded on the moon for ten years as a consequence of stealing her uncle's rocket and not heeding her brother's warning. Her disappearance caused a decade long rift amongst her family, and her three children grew up without her.
Amelia Hughes has spent decades trapped on a supernatural train that will not release her until she can learn to let go and move on from her husband's death as well as grow into a better person. But she still hasn't.
Spinel had been left abandoned and alone on a floating garden in space for six thousand years by her "best friend." Until the ugly truth had finally been revealed to her, she spent all that time never fully comprehending that no one was coming for her.
Why is "character gets stranded/trapped someplace for a very long period of time" such a common trope in modern cartoons. And why does it destroy me EVERY. SINGLE. TIME?!?!?