One particularly interesting idea that came out of this discussion was Dillon's suggestion that meeting places for lovers who had good relationships would be doomed - something bad would happen there later. But if it is a place associated with evil/bad/doomed relationships, then...that place will be preserved forever unchanged for all of Middle-earth's history. Sort of a 'nothing gold can stay' approach to beauty, goodness, and love in Middle-earth, with a heavy sense of loss hanging over even the beautiful parts.
So far, we have:
Nan Elmoth, meeting place of Thingol and Melian --> Eol's abode, a forest of entrapment
Nevrast, meeting place of Orodreth and Meril at the Mereth Aderthad --> city abandoned
Tarn Aeluin, meeting place used by Andreth and Aegnor --> massacre of the outlaw band by Thuringwethil
Glade where Beren and Lúthien first meet near the border of Neldoreth --> destroyed by Carcaroth
Pools of Ivrin - we haven't written Finduilas' romance with Gwindor yet, but presumably this location will feature? --> destroyed by Glaurung
To be contrasted with:
Tol Morwen - near the meeting place of Túrin and Nienor (which was Finduilas' grave), their memorial stone survives the drowning of Beleriand
Himling - eh, whatever the relationship between Fingon and Maedhros is, it certainly isn't going to end well in the Nirnaeth, and they've been apart all along
Tol Fuin - romance of Gorlim and Eilinel in Dorthonion
It's not a perfect correspondance, but again, we're only going for an impression of loss, not a hard and fast rule.