i always wondered if you guys knew what i was talking about whenever i called sakura a yandere

welp here something i found that tells it better than i can

"Yandere is a portmanteau of two Japanese words. The first is yanderu, which means “to be sick,” and the second is deredere, used here for “lovestruck.” A yandere is often sweet, caring, and innocent before switching into someone who displays an extreme, often violent or psychotic, level of devotion to a love interest."