Nimrodel had lived in Lothlórien before the Sindar and Noldor were seen in the forest. She was unhappy with these newcomers, as she thought they would bring the turmoils of Middle-earth to the golden forest. She lived separately near the river that would later bear her name, and spoke only her native tongue. The only good thing she saw in Lórien was the Sinda Amroth, the King of the Wood. She loved him, and he loved her, but refused to marry him.
After the Balrog awoke in nearby Khazad-dûm in TA 1980, Nimrodel grew even uneasier in Lórien. She fled, and made her way to the edge of Fangorn Forest, but could not enter it. Amroth found her, and promised her peace. Together they would travel to Edhellond, the port city in Belfalas, and thence set sail to the Undying Lands. They were accompanied by a small staff of Silvan Elves, including Mithrellas. All went well until they reached the White Mountains in TA 1981. The group became separated and Amroth reached Edhellond well before the others. He decided to wait for his love aboard their ship. When a storm broke looose and swept the ship out of port, Amroth leaped overboard, hoping to swim back to shore. But he was quickly taken by Belegaer's strong currents and drowned.
Nimrodel, in the meantime, had settled for a while at the river Gilrain, which reminded her of her home. She sat by the starlit stream and fell in a long deep sleep. After she woke, she journeyed further, but found no ship in Edhellond, and Amroth was long gone at the bottom of the sea.