: Well, why only Luthien and Beren? Maybe he wanted to have a more "Philemon and Baucis" sort of stuff-which would be the opld Tolkien couple. Whatever
: Regarding Goldberry, she is the Riverwoman´s daughter. So maybe we should ask ourselves who the Riverwoman is???
: O.K., WHO IS SHE?

There is no particular reason why Tolkien might not identify himself and his wife with other characters in his stories - though the only one for which there is any evidence is the Beren-Luthien one.

As for Bombadil and Goldberry they don't fit very well into the rest of what we know of Arda, hence the debate.

From an external point of view they are easily placed as forms of the nature spirit found in virtually all mythologies. Bombadil is a genius loci, a Green Man, Boggart or whatever you like to call him, Goldberry a water nymph or Lady of the Lake figure. Their genesis seems to have been outside the development of Tolkien's main mythology; then later inserted into it, with certain difficulties which Tolkien never resolved (at least publically). Tolkien was obviously quite happy to leave both characters as enigmas.

Retuning to the "Internal" question, Goldberry's ancestry could be merely metaphorical - "River-daughter" as you might describe a sailor as "A son of the sea." Or if the Maia could reproduce she might be the progeny of two of the followers of Ulmo. Tolkien never really fully made up his mind as to whether his "Angelic Spirits" could reproduce - Melian did and so apparently did Ungoliant - though this was with due to mating with corporeal beings. At one stage Eonwe was going to be the son of Manwe and Varda, but this was later dropped.

So basically you can believe whatever you prefer on the whole subject.