翻臉不認人 [－脸－认－]

Jyutping faan1 lim5 bat1 jing6 jan4
Pinyin fān liǎn bù rèn rén

Definitions (CC-CEDICT)
  1. to fall out with sb and become hostile
Definitions (Wiktionary)
  1. phrase, idiomatic
    to do an about-face and become hostile or cold to someone