But in the end, it all makes sense, and that's great.
People praise _Bakemonogatari_ for its interrogation of the Tsundere stereotype and what it would take to make a person behave like that. _The Future Diary_ does something similar for the Yandere.
Also, it has the stones to say it's going to make you root for the Yandere, which is shocking.
Now, there's no way that Amano and Gasai's love can not be fucked up. But even so, you want them to have some happiness.