昨天的誓言今天的谎言
[zuó tiān de shì yán jīn tiān de huăng yán]
Translates directly as 'yesterday's vow, today's lie'. It depicts inconsistency between words and actions over time, especially the change from promise to deceitful falsehood. A way of conveying frustration about dishonesty, unfaithfulness and unreliability encountered in reality or human relationships.