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...艾萨克觉得这份工作实在令人难以忍受，就辞职走人了。He had not expected the pain to be unendurable...他没料到会如此疼痛难忍。