"The changes that occurred were like changing a human into a wolf, but much more painful. It was like nothing I'd ever experienced; the pain lasted for days. When I woke, I was different. I'm not a vampire, I'm still a werewolf, but the blood made me a little, well, vampire-ry."
"Like a hybrid?"
"Exactly. I'm stronger than a werewolf, I gained vampire speed, my aging has slowed and my bite is toxic to werewolves now. It doesn't kill them quickly like a real vampire bite would, death takes a week or so. The change is permanent; I didn't regret it until I saw you that night, because to bite you now would doom you to a slow and painful death."
She would never be able to complete the bond. No wonder she thought I would reject her. "You can't bite me, but I could still bite you?"