No offense, but you just perfectly encapsulated the big problem with this kind of concept: it completely, utterly disregards the feelings and opinions of the women in the story, treating them more as objects than actual people, a commodity to be traded around for your entertainment. There may be a historical precedent for that, but it's not even remotely close to the theme and ideas I want to convey with LLtP.
By sleeping around in this story, you are going behind the backs of almost all the women you flirt with. They're not going to just go "oh, okay" when they learn about this. More likely, they'll be furious with you. You'd be lucky to keep any relationships at all. Only in those cases where the women were already clearly accepting of this, such as with Lilith/Selena or Belle, does this work. Or if you accept a demon's essence inside your mind and body, corrupting your thoughts and emotions and turning you into a power-mad despot perfectly willing to erase people's personalities to turn them into your idealized version of who you want them to be.
Edit: Oh, and as for the truthsayer hereditary thing, the game strongly implies that truthsaying tends to become latent in a bloodline, emerging only occasionally and randomly. Neither Selena nor Lilith are truthsayers, yet they both carry that ability inside them for their progeny to maybe inherit (or at least carry on to their offspring, and so on). The challenge isn't to find someone with truthsaying in their blood. The challenge is to find someone who actually gains the effects of this mostly latent ability.
