If you describe a bad situation as unendurable, you mean that it is so extremely unpleasant that you have to end it.
例句
Isaac had found the work unendurable and walked out of the job...艾薩克覺得這份工作實在令人難以忍受，就辭職走人了。He had not expected the pain to be unendurable...他沒料到會如此疼痛難忍。