I think there are two main reasons our entire pop culture at the moment is consumed by vampire boyfriend/werewolf boyfriend. The first is that we're only afraid of three things -- sex, death and life -- and we'll do anything with our imaginations to cross from here to there to feel safer around them. Vampires = sex + death (an end to a start, the joy in being consumed utterly, burned alive; to be awake when the world is sleeping and thus asleep when the world is awake; to be dead to the world) and werewolf guys = sex + life (overly lush, too accepting, too much like life on V, fucking in the garbage and the sunlight).
The second one, though, and it's kind of central to this episode, has to do with feminism, particularly our generation's bizarre experience of feminism as culture speeds up. Vampires, in this particular brand of literature, are paternalistic/"protective," seductive/"mind-controlling," bad boys-except-with-you types; like keeping a tiger in the kitchen, or Tank Girl, they're the giant scary thing that loves only you and can kill everyone else. And then there's the werewolf guy, who just wants to romp around all romantical and dedicate himself to you utterly and says "More life! More sex! More fun! Love who you are! Get lost in it!"
And for those of us who make a habit of sleeping with men, these are the ways we're trained to respond to men: as cold and controlling authorities by virtue of their physical power, or as exuberantly terrifying, conspiratorial beasts lacking any sort of self-control. Vampires are nice because they are courtly, and old in the ways that count while being forever young and hot in the ways that really count, and rich, and do things like come zoom-running from miles away and holler about how you must be protected and stand outside your house all night, staring. Vampire guy can make you be turned on, so he removes any kind of sexual risk or shame; you never have to ask for it and if you do it's because he made you want it; all you have to do is lie there and be penetrated. The downside is, they never ever go away.
Werewolf guy is nice because he says, "If it feels good, do it!" Be super psychic, yell at Andy Bellefleur, make out when you wanna make out. Werewolf can guy can smell that you're turned on, so you don't ever have to admit it: he carries the sex monster for both of you. Werewolf guy knows better than you about the beast, because you've never been allowed to let your beast free. So he urges you to do so, and shows you how to do so, and it's very fun and not very memorable because we don't live in memory, we live now. He changes shape to be something closer to what you wanted, what you thought was perfect -- the same way you change shape for vampire guy, because there are rules that must be followed. Vampire rules are the rules of the world and of the night, Saturnian and Jovian, hard and fast; werewolf guy rules are the rules of the heart. Downside is, they go away. Werewolf guy is just as fickle as you are, or would be if "fickle" were a word that applied to men, because werewolf guy is a horndog, who loves you eternally until he turns his head or else can eternally love any number of people in this world -- which contrasts absolutely with the singlemindedness of vampire guy, who's crossed oceans of time, who's been waiting... Oh, just hundreds of years for somebody just like you. Vampire guy conspires with time itself.