I have not seen the entire movie, but from the snippets I have seen and the Wikipedia and other plot summaries, the movie does contain eroticism and violence but doesn't seem to involve rape.
Why such a title then?
The Wikipedia synopsis for the film seems to indicate that the film is named for the events which allegedly lead up to the first short:
Four sisters living in an old château are convinced that they are vampires. One believes she was raped by the villagers years before, and is blind; another is afraid of sunlight, and they all react violently to crucifixes.
And in the end:
Thomas asks one of the sisters to bite him to prove her wrong and discovers she is, in fact, a vampire.
Which would indicate it's probably true.