By Neil Gaiman
In the book, Coraline moves into an apartment with her mother and father. She was easily bored, for her parents were too busy to spend time with her. Coraline discovers a door that leads to another world where her "Other Parents" are. They would always spend time with Coraline and flatter her. However, they insist to her she should sew own buttons to replace her eyes so she could be with them forever. Coraline refuses, growing uncomfortable. She leaves the other world. She then discovers later on her real parents were missing. She sees them stuck in the mirror, pleading for help. Coraline goes back into the world to save her parents, and sees the Other Mother's true form.
This scene in the book is important because it shows Coraline's care for her real parents, despite the fact the real parents barely spent time with her. She could've accepted the Other Parents' offer of sewing on the button eyes and living with them forever, but she did not. She could've left her parents be in the mirror and not enter the door that lead to the Other world with the Other Parents, but she went inside again instead.
This shows her care for her real parents, and how she wouldn't trade her real parents for anything in the world.