The Dark Lady's heart was captured, and they became lovers. And then one night (...) they lay together in the fashion of a >man and a woman. But Perenelle had been a virgin until that night.

I get what is meant, but if they had been lovers for some time then I would say that Perenelle was not a virgin in any meaningful sense of the word. Of course, from an old-fashioned point of view she might have been, but this sentence is not accompanied by a modifier expressing the change in values as the next one is.