It's rude to leave your friends behind
Janet and her friends went to the dance together because they were all nervous to go by themselves.
Janet wants to go home.
Janet tells her friends that she wants to leave and asks if anyone wants to come with her.
Janet doesn't want to dance anymore, so she leaves and goes home without telling anyone.
Janet's friends decide to leave with her, and they have fun together elsewhere.
Janet's friends are worried about her and are then annoyed when they find out she left without saying anything.