During her stay one of the tribe's elders decided she had had enough and told the tribe so. They started their ritual and held a feast for a day or two where everybody peacefully said goodbye to the old woman and on the morning of the third day the tribe moved on and left the old woman behind in the desert to die in peace.
However the aid worker couldn't accept this. The woman was still alive! She could go on for at least a few more weeks, maybe even months! So she frantically ran back to the tribe pleading with them to let the old woman live. The tribesman were confused and tried to calm the aid worker down. It was all good! They had said goodbye and she had led an amazing life!
When it became clear she couldn't convince the tribe of the error of their ways, the aid-worker went back to the old woman and stayed with her to comfort her until she passed away.
The aid worker never realized that she was the one being comforted.