Solve this riddle to find out
This is a story about a girl.
While at the funeral of her own mother, she met a guy whom she did not know. She thought this guy was amazing, so much the dream guy that she was searching for that she fell in love with him immediately.
However, she never asked for his name or number and afterward could not find anyone who knew who he was.
A few days later the girl killed her own sister.
Question: Why did she kill her sister?