Complex sentence: Aryana, who doesn't know that she is cursed to be a mermaid when she turns fourteen, faces her destiny of being a mermaid, and is torn between choosing the sea where she belongs or the land where her heart belongs.
Split into simpler sentences: Aryana, who doesn't know that she is cursed to be a mermaid when she turns fourteen. As she faces her destiny of being a mermaid, she is torn between choosing the sea where she belongs or the land where her heart belongs.