What is the main idea of this lullaby by Sarah dessen?

I believe the main idea for this story would be how love can affect people's lives and how it can influence it.

For example, Remy's mom belief in love influences the way Remy's life is shaped because she ends up not believing in it since she constantly sees it falling apart. This ends up affecting all of her future relationships. But also, in the end, Remy's new found belief in love brings her back with Dexter. So love had a huge influence in the characters in this story, in different ways.

Hope this helped