Jay is your boyfriend and aware of you being vampire, but not his friends. Because of your vampire peculiarities there's no pic of you with Jay, because you are not reflected in the pictures. And you active only at night. Which made Jay's friends suspicious about him having a partner cause they never saw you and Jay have no pictures with you. That's why he invited his friends to his place, to meet you with his friends. Meanwhile you being vampire menace, stealing his underwear.

"Hey, give it back, blood sucker! Guests will arrive soon!"