Yes, this aspect of it is of course one that we as mortal being can't possibly see the same way as immortal beings would. It had bothered me for a long time---decades, in fact, though that probably sounds absurd---because Tolkien himself offers nothing in the way of an explanation for their separation, acts as though it were just perfectly normal; yet in other parts of the narrative, when there is a separation or sundering between companions, as when Frodo leaves the Shire to take ship at the Grey Havens, there's a very careful explanation of why it is that he can no longer stay. It seemed as though either I was missing something or, much worse, that it was simply going to be Just One Of Those Things, and I would never get an answer. So I'm very glad to have one that really does make sense of it all...
But Elvenholm and Valinor aren't the same place, are they? I had believed that Valinor lay well to the west of the Undying Islands where the Elves lived who had never gone to Middle Earth... it's been too long since I read the Sillmarilion (never really got into it the way I did LoTR---found it too much of an endless series of chronicles, with few if any emotional hooks to the storyline). I had thought that Elvenholm had been created specifically as a home for an immortal race (the Elves) who were however not on the same level in Tolkien's hierarchy of beings as the other immortal races (the Valar and Maiar), that Valinor was reserved for the latter, so that there had to be a place where the bottommost order of immortal beings got to live, just as there was a place for the topmost order of mortal beings (Numenor, for the Numenorians) separate from Middle Earth, which was where we miserable lot came in... I guess I'd better reread the first part of the Sillmarilion...
Well, I'm really happy with Blotan's story and figure that it's probably the best shot at the answer.
