悲哀常常紧随快乐。乐极生悲。

Grief often treads upon the heels of pleasure.

我有一种乐极生悲的感觉。

I have a sense something bad will happen.

快乐，是人之所求，但太乐则乐极生悲。

We seek happiness, but too much of it leads to sorrow.

过度耽于享乐的结果，往往导致乐极生悲，以至最终影响到日常生活的运作。

Over indulgence in joy will cause sadness, which eventually disturbs the normal life.

老虎捕到了獐子高兴万分，却没料到中箭而死，真可谓是乐极生悲。

The tiger was overjoyed at catching the river deer, but it didn't expect to be shot to death. Extreme joy begets sorrow.