She must have researched so hard on how to be a Yandere, and it all came to be useless in the end.
I would stare like that too and think "What about all my plans? I even bought ropes, chains and drugs? I spent hours researching, I even readied cameras and GPS, what about all my money? What do I do with all the knives now? Should I just let that girl out of the basement now? Wait didn't I prepare Blackmail with their parents? They haven't seen it yet right? Do I have time to get it back before they get home?"