[Lalaith]

I didn't know that about Idril. Thanks for that. And don't forget your namesake, Morwen...who I think was one of Tolkien's most intriguing female characters.
I would actually quibble about your point, however, of women not having strong roles in the literature of Tolkien's sources. There were an awful lot of women appearing in old Norse literature and poetry, and some of them were damn scary, I can tell you. Very few 'lady-loves', actually.
The Finnish Kalevala, too, had very strong female characters, although of a different and more 'enchantress' type nature.
The lady-love prototype came in during the high-mediaeval period of literature. Tolkien certainly looked at this era (re his translation of Sir Gawain and the Green Knight) but his main period of interest was earlier.