Personality Test

The answer and explanation are in the comments. (Update: I have removed the answer from the comments at the request of someone who thought it would result in people not thinking about it enough). Below is the question sent to me by Nell yesterday.


A woman, while at the funeral of her own mother, met this guy whom she did not know. She thought this guy was amazing, so much her dream guy she believed him to be just that! She fell in love with him right there, but never asked for his number and could not find him. A few days later she killed her sister. Question: What is her motive in killing her sister? (Give this some thought before you answer.)