But I have to wonder, why don't these writers put a tiny bit more effort into the blackmail. She sucks the dude's dick because of a Photoshopped picture? Absolutely nonsensical.
Even if you want to keep her 100% "pure", give her a sibling or a friend who isn't so pure, and has something that could be used to blackmail the main girl. It's absolutely dead simple. I really don't get it.