I don't quite understand what happens to Arwen?

[Arathiriel]

He was given this choice because one of his parents was mortal, one was an elf, so the Valar gave to him and his brother the aforementioned choice. If she chooses to be mortal, she will still have long life, but will eventually die

Actually the Valar are not gods but rather they like angelic beings who govern over the world of Arda...

And it was not the Valar who gave Elrond, his brother, and children their choice of choosing between being of the Elves or of Men but rather it was Eru, the Creator of ME.

The Valar cannot give or take away immortality or mortality for any being but instead it is only something that ONLY Eru can grant or ungrant as the case maybe...

[ January 16, 2003: Message edited by: Arathiriel ]