[Lalwendë]

Isn't Death somewhat different for Aragorn compared to other mortals? He is descended from the Numenoreans who originally were given the 'gift' of choosing when to give up their lives - which as a result could be very long; it was when the Numenorean kings started to resent the need to make a choice on when to die that their lives started to become shorter anyway - thus taking the decision to love a long life away from them anyway.

I'm not sure that it says anywhere in the text whether Merry and Pippin had grown physically old by the time they left for the south and their deathbeds - it doesn't even say whether they died at the same time. As far as we know they simply knew they were getting old and so decided to spend their last years elsewhere, eventually to be buried there.

It does seem that Aragorn did remain relatively 'youthful', much as the old Numenorean kings may have done, and like a good king, he did not shirk taking the decision of when it may be the right time to make way for his son. I do find it interesting that while Aragorn fully accepts that he must make this decision and he accepts it with good grace, Arwen finds it much more difficult and lingers for quite some time, as though she can't quite shake off what she had accepted through the long years before meeting Aragorn would be her 'fate' as an Elf.