If you talk about the transience of a situation, you mean that it lasts only a short time or is constantly changing.
例句
There is a sense of transience about her, a feeling that she has only stopped off here en route to another place.她给人一种转瞬即逝的感觉,仿佛她只是在前往他处的途中在此略作停留。...the superficiality and transience of the club scene.夜总会生活的浅薄与无常
英英词典释义
Noun
1. an impermanence that suggests the inevitability of ending or dying