If my girl was being fucked like this by a black guy I would ask if he could fuck my ass next. That would be the ideal move for an alpha male. Fuck the white guy to show supreme dominance.
He's rightly humiliated in the presence of that strong, dominant Black cock; most white "men" have had the experience of being humiliated when we see Black studs' superior cocks. This lucky lady is rightly appreciative of the superior experience of taking a BBC.