In RoTK, Many Partings, when Aragorn says farewell to Celeborn: 'But Celeborn said: "Kinsman, farewell! May your doom be other than mine, and your treasure remain with you to the end!"' I'm guessing he meant Arwen. I guess we must assume that since Arwen spent many years in Lorien, there is a special bond between her and Celeborn. I think it is odd that Tolkien had Celeborn say these words, and not Elrond. Elrond was still with the travelers, yet no mention is made here of Aragorn saying any special words of farewell to Elrond (or Gandalf, for that matter).