Can anybody get this right?

My friend was over at my house last night and she asked me a riddle, and I was the first person in probably 50 some years to get it right   This riddle was developed by a world-renowned psychologist to test on murderers. I know, it sounds crazy, but now my friend thinks I am crazy. Apparently, the people that were asked the riddle and got it right ended up being murders and sent to jail in their lifetime. If you were to get this riddle right, that would mean that your mind was compatible with that of a psychopath (I've been telling people I was crazy but they wouldn't believe me). I know this may sound a little bit suspicious and maybe my friend was lying, and I had my suspicions as well, but still, it is a little weird. I will let you know if you can get it right! Here's the riddle:


A woman is at her mother's funeral. There is a man there and she instantly falls in love with him. She thinks he's the perfect guy and he has no flaws. However, she forgets to ask for the man's phone number. Three days later, the woman kills her sister. Why did she kill her sister?


Good luck!  

Cause if the guy was at her mothers funeral, he'd be at her sisters.

I'm thinking it's too easy though. Am I missing something?

Yeah you got it right Nikki, I thought it was obvious, but maybe that's just because us Fury pirates are so smart  

The guy comes to the second funeral.
 
This time she gives him her business card and writes on the back:
 
Call me maybe -- no, call me, do it!
 
He likes her attitude and things start going.  Great, right?
 
Except...
 
Two days later the woman is killed.
 
Someone else at the second funeral also saw the guy and decided he was Mr. Right.