Ooh la la, Lúthien...

[Aiwendil]

It seem that Tolkien loved the idea of Edith more than the reality.

Indeed. For that matter, I would say that every feeling anyone has for anyone else is actually for their internal 'idea' of that person rather than for the external 'reality' (if such a thing can even be meaningfully talked about). All that varies is the extent to which that internal idea gives a reasonable approximation of the person's behaviour.

In other words, I think Tolkien's idealization of Edith/Luthien is nothing unusual - which, I suppose, makes the story of Beren and Luthien that much more universal in its appeal.