Teleri requested something about Arwen and mortality.
She'd imagined the pains of old age would sorely try her. That stiff joints and a body heavy with years would make life joyless, that the mirror would become a trial.
The years pass. He grows grey; burdens etch themselves upon his brow. But Arwen remains unmarked; the mirror is indeed a torment that teaches the truth of mortality: that bodies go their own way, whatever will desires. And so she veils herself.
Aragorn teases her at first, then cajoles, argues, finally grows quiet. And in the new loneliness that's crept into their looks, she tastes the bitterness of dying.