蓝颜知己红颜知己
[lán yán zhī jĭ hóng yán zhī jĭ]
"Blue-Faced Soulmate and Crimson-Faced Soulmate": Refers to intimate yet platonic friends of opposite genders, emphasizing deep connections and mutual understanding beyond simple friendships. Here, 'blue' typically symbolizes males and 'crimson' for females.