are you a psikopat?

just now, my friend, Hans, gived us quiz to determine whether you’re a psikopat or not…..
here’s the question:

there’s a mother with two daughters. in the day their mother dead, there’s a vuneral.. of course, right?! in the vuneral, there’s a charming man… the old daughter looked at him from a distance.. not long after that, she saw her sister (the youngest) was talking with the man…. not a just talking, but a nice conversation that seems no end….
two weeks after the vuneral, the old daughter killed her sister…..

in your perception, what was the reason of the oldest killed her sister?? fill-in the comment below…