Erica was surprised as so much happened that night and she was clueless about all of it and did not have any idea as she left the very next day.
That day Lisa told her, she and Steve planned to have sex and she was looking forward to it.
After they were announced prom king and prom queen, Erica knew now they would be going away somewhere.
All these years it was very painful for her to see the love of her life being with someone else but she beared with it and tried to be happy for them but now she couldn't take it anymore and she left the prom and went back to her room. She had no partner to attend prom with and she attended it alone, so she did not have any obligation to stay there, so she left for her home.
That night Erica cried a lot assuming Steve and Lisa were having sex.
Erica felt petty but she couldn't help but feel bad, she pretended like she was sleeping in her room but she played some songs and heard them while crying.