Boats travelling up and down Anduin and Lorien's isolation.

[Zigûr]

Originally Posted by Faramir Jones

One could perhaps blame Elrond and Galadriel somewhat, for not offering the rulers of Gondor and Rohan regular advice and intelligence reports.

It might be a recursive situation: did communication fail between the Eldar and Gondor because of the estrangement, or was the estrangement caused by the lack of communication?

I think a substantial reason might be that for the majority of the Third Age the threats appeared to be deriving from different sources: Arnor and the Elves were troubled by Angmar and Dol Guldur, while Gondor fought the Haradrim and the Easterlings. Gondor's wars were also largely Sauron's doing, but less openly.

The relationship between North and South seems to have failed after 1975 when Gondor and the Elves destroyed Angmar. Despite their victory, the North-kingdom had ceased to exist, which may have severely limited any existing relationship between Gondor and the allies of Arnor in the north. Although the Nazgûl conquered Minas Ithil in 2002, Sauron retreated from Dol Guldur in 2063 (a side effect, and possibly an unfortunate one, of Gandalf's investigation there). The Watchful Peace ensued. It seems possible to me that, with Arnor gone and the West at (uneasy) peace, the Men of Gondor had no apparent reason to maintain contact with the Elves, and thus lines of communication failed. Even for the Dúnedain the ensuing four hundred years of peace would have seen several generations of Men come and go. By the time Sauron returned to Dol Guldur in 2460 and the Nazgûl began attacking Osgiliath in 2475 the relationship between Gondor and the Elves may have been virtually nonexistent because they had not needed one for about four centuries.

Originally Posted by Pitchwife

As we see here they had some folklore about Lórien and were probably aware that it was Elvish land, but their yearning to catch a glimpse of its beauty was mingled with fear, and their first reaction to the spreading mist was dismay at being touched by Elven magic.

It's interesting to think that as Lórien was the first Elven realm heading north on that side of the Mountains, it may have been the main "contact" that many Men in the South and along the Anduin had with Elves or Elvishness, and its seemingly strange and unsettling qualities may have hindered an ongoing relationship, particularly as time passed and the lore of Men failed. Probably a reason the relationship between the Lake-Men (and, one assumes, the Men of Dale before them) and the Elves of Mirkwood was so much stronger and more comfortable than any between the Men of Rhovanion or Gondor and the Elves of Lórien was because there was no Ring in Mirkwood and therefore such "magic" was much less common and noteworthy.