The dilution of Elven blood and subsequent mortality

[cellurdur]

Originally Posted by Pervinca Took

I assume Mithrellas would have renounced immortality by her marriage to Imrazor, although, like Arwen, she would not have aged as quickly as them, so might indeed have wished to avoid seeing them die.

An elf cannot renounce their immortality anymore than a Man can decide to be immortal. It's quite impossible. There have only ever been two exceptions to his: Luthien and Tuor.

If the story of Mithrellas is true then would have returned to Aman at some point or wandered alone in Middle Earth forever separated from her husband and children.

As Mithwalen said mortality if the default setting for everyone with mortal blood, unless some other doom is given to them.