Complex sentence: She is so happy she goes into the bathroom and writes in her diary for a long time Lilly being annoyed that Mia is hogging the bathroom to write she asks in disbelief why Mia hasn't figured out that her Talent is her writing.
Split into simpler sentences: She is so happy she goes into the bathroom and writes in her diary for a long time. Lilly, being annoyed that Mia is hogging the bathroom to write, asks in disbelief why Mia hasn't figured out that her talent is her writing.