serial killers Psychology - must read

Read this question, come up with an answer and then scroll down to the bottom for the result.This is not a trick question. It is as it reads. No one I know has got it right.

A woman, while at the funeral of her own mother, met a guy whom she did not know. She thought this guy was amazing. She believed him to be her dream guy so much, 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 for killing her sister?

[Give this some thought before you answer, see answer below]
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ANSWER:
She was hoping the guy would appear at the funeral again. If you answered this correctly, you think like a psychopath. This was a test by a famous American Psychologist used to test if one has the same mentality as a killer.
Many arrested serial killers took part in the test and answered the question correctly.
If you didn't answer the question correctly, good for you.
If you got the answer correct, please let me know so that I can take you off from my email list..