Hello. You did not enter the text to which this question refers, which makes it impossible for it to be answered. However, when searching your question on the internet, I was able to find another question like yours, which showed that the text in question is entitled "Blue", written by Francesca Lia Block. If that's your case, I hope the answer below can help you.
La's mother decides to leave, before La can even say goodbye to her. The mother's departure changes the whole emotional state and daily life of the family. This attitude becomes a major trauma for La's father and for the life of La herself, who feels extremely sad and confused. The impact of La's mother's departure is what moves the plot of the story, because all of La's actions, all the motivations, the conflicts that she gets involved in and even the appearance of Blue, a strange creature that tries to console La, happen as a result of her mother's actions.
