A possible origin of the Yandere tropeYandere may have emerged as a deconstruction of the Yamato Nadeshiko archetype: a eternally serene woman who always puts the needs of her family and husband before her own. A yandere is all driven to the logical extreme and then examined realistically: a sentient individual put in such position would invariably experience enormous strain. Sooner or later she would snap at a slightest provocation. Ironically, it is this realistic take that makes a yandere so endearing to the audiences, often even more so than the traditional Yamato Nadeshiko. (Granted, there would realistically be a wide range of possible responses other than going Axe Crazy, but this one is definitely the most entertaining to watch!). Compare with the Violently Protective Girlfriend who can become Axe Crazy when the love interest is in danger but is otherwise MUCH more stable mentally. See also Living Emotional Crutch for a reason why she goes from affectionate to murderous.
Why Yandere can be perceived as attractive