I've just re-read Fire and Hemlock, which is powerful stuff. The version of Tam Lin it refers to is the one I knew, which has a Fair Janet as its heroine.

Does anyone know the version of Thomas the Rhymer which has him going back to Faerie?

The stories I was recalling turn out to be the variations on the Bull of Norrowa, Beauty and the Beast, etc - one of them, East of the Sun and West of the Moon, is referred to in the book, where the woman does something forbidden which nearly results in her losing the man, and him being well and truly lost. They go back at least as far as Cupid and Psyche, which is not only about the apotheosis of Psyche, but also about Cupid breaking free of his mother's control. Much more relevant to modern life than the Queen of Elfhame, but even more difficult.

Penny