I believe that Arwen was still longer-lived than Aragorn because of her Elven blood even though she renounced it for a mortal life to marry him.
From how I remember it in the book ... after Aragorn has died she goes into a deep mourning for him, only staying for the sake of her eldest son who accedes to throne and to help him take up his duties as the new king. I can't remember how long she remains after Aragorn's death but I
do recall that one day she simply lies down and wills herself to die.
It was a very powerful piece of imagery which Tolkien wrote as it's left a lasting impression on me to this day and bear in mind it's been more than twenty years since I've read the books!
I'm sure others will know the details with more clarity than I do so please ... correct me if I'm wrong!!
The Silmarillion ... yeah ... strange stuff and a lot of navel-gazing if you ask me! Sorry if I offend anyone, there's more entertaining stuff to read out there than that particular tome I'm afraid.
