In modern media, vampirism is seen as an excuse. Vampires are immortal, undead, and generally younger-looking. This not only gives the excuse for pedophilia – both an immortal with a barely-legal love interest that looks like an ethical relationship, as well as an immortal who was turned when they were still a child so while they are technically legal it looks unethical.
It’s a big grey zone, but these relationships are pedophilia-coded, both with the giant age-gap and with the child-coded immortal.
Much less common, but still present, is the incest-excuse. Because these beings aren’t actually alive, technically there isn’t any incest because their family-relations are less- or not-important.
I have found only one vampire-relationship that wasn’t pedo- or incest-coded, and that one’s written in purple on the book. This still romanticizes vampirism, but it doesn’t dip into theose more dubious, illegal relationship tropes. It’s also the only homosexual relationship on the list.