[ Women, perhaps, are less trouble than another man has always proven to be, but he will never accept his sister giving up any more of herself to another person. Nothing about their relationship would or ever will allow him to let Rebekah have anything close to friendship on a long term basis - let alone with something as breakable as a human girl.
Sometimes he can convince himself that it's for her own good, that he still remains her only true protection in this world against their (his) enemies. And if he's unable to, it doesn't matter. They've lived this way for centuries. They are family, he forgives her for her failings.
Nothing will change.
Satisfied with Quinn's answer he ignores Rebekah's look - other than to shoot her a grin, and then patiently waits for the song to begin. ]