Question for the Black Only Ladies: Why...?

I have noticed that with so many white women, ounce they go black they evolve sexually into women that wants to reserve their bodies exclusively for black men, at least outside of their white boyfriend or husband. More than that even, you women seem to take such pride in your refusing to allow any men who are not black inside you, I amazed how important that seems to so many of you. Does being with a black man give you such a sense of pride that you feel to good to lay with men who are not black, or what is it exactly? I completely respect the attitude and even find eroticism in it, but intellectually I would just really like to know, why the evolution?:)