It could be that the girl is leaving because she's not happy with the situation in the cartoon. Or perhaps she's been called away for some urgent matter.
The girl might be leaving the cartoon because her adventure in that place has come to an end, or she could be moving on to a new and exciting chapter in her story.
Perhaps the cartoon girl is leaving to pursue her dreams or to be with her loved ones. Who knows exactly, but it's likely something significant driving her away.
Maybe she's going on an adventure or has some special mission.
Maybe she has an appointment or needs to run some errands.
Maybe she's found a better connection or a new opportunity with that guy.
Maybe they are not having fun or there's some problem in the cartoon world that makes them leave.
Maybe the kid is leaving because he has to move to a new place with his family.
Maybe there's a problem in Springfield that's making them uncomfortable or they're following some kind of scent.
Maybe the class is over and it's time to go home.
The cartoon woman might be leaving the door because she received a call or invitation. Or perhaps she's simply following a routine she has every day.
Maybe the kid is going on an adventure or to visit a friend.