why do elves need to go to the undying lands?

[stevensimth3675g]

Elves are indeed immortal in the sense they won't die of old age, but they can die from grief or severe wounds. The journey to the Undying Lands allows them a peaceful existence without these woes. When Elrond talks about his daughter's "death", he means her choosing a mortal life with Aragorn, which will eventually lead to her physical death, something Elves aren't accustomed to. It's a metaphorical death from his perspective as an immortal being.

[Abdullah89]

In spite of their slow aging, elves are tied to the earth. In the folklore that has been established, this is why there aren't even a few elves left around today. As they get older, their spirits take control over their physical bodies until they are only spirits. The Elven Rings' strength at Rivendell and Lorien prevented what is known as the "fading of the elves" from occurring there.
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