@BlazingMagpie: China's common stories (in TV dramas and such) are like: the MC (males, of course) can be either a pathetic guy (but will become OP in the future) or out-of-the-box son of a rich (noble) family, he has girl A who loves him unconditionally, willing to do everything to him (in some cases, they even engaged), he promises this and that to her, that he only loves her, that he will make her happy etc,... Until he meets another woman (usually girl A's friend/relative/real sister/long lost sister/sister from different mother/etc.) Then the MC and that woman will fall in love, and they live happily ever after. Girl A will be called an annoying woman who disturb their love. It's often that on the climax, girl A will be kill by either MC or his woman.
Thus, siblings killing each other for love is normal in Chinese's stories.