The same reason you said you wouldn't have... 'mated' with him if you had known. [She might not be anything remotely human, but that had sounded like some sort of boundary at least. Maybe, despite herself, there was a little understanding in it.

She almost laughs again, but takes a deep breath instead.] But I knew something was off. I'm an angel, Li... I've had my fair share of demon experiences. [No, okay, she does laugh, but it's incredibly harsh for herself and clipped.] Hell... I spent years with one, in bed and out. [Not something she's admitted to too many people; its definitely not something she's proud of.] Styxx is nothing like that, and to let it all go down the way it did and then... to feel him wake up and panic...

[She had hurt him, plain and simple, by falling into a trap she had set for herself.]