机关算尽太聪明，反算了卿卿性命 (jī guān suàn jìn tài cōng ming , fǎn suàn le qīng qīng xìng mìng): if one is too calculating, it will be the cause of one's own undoing (famous line in "A Dream of Red Mansions" 紅樓夢|红楼梦[Hong2 lou2 Meng4])