For me, the most unbearable thing is .

最让我不能容忍的是，用英语怎么翻译?。

The most unbearable pain in the world is to be parted in life, and separated by death.

世界上最令人悲痛难忍的，莫过于生离和死别。

Finally I know what Romain Rolland had said:The most unbearable pain may be what you want to do yet without practice.

终得体会罗蔓·罗兰说的那句：“最难忍受的痛苦，也许是想干一件事却不去干。”