I've been in an interracial relationship for ~5 years now (I'm white, she's Asian) and anytime we go somewhere with large numbers of people, we talk about the number of mixed couples or children we see walking around. Perhaps we're a little more attuned to it since we fall in that demographic but it really is striking to see such few couples where a white man is with a black woman, especially in comparison to white women and black men. (Another huge disparity? White men with Asian women are way more common than white women with Asian men)
I won't pretend to know why it happens like that but it really is interesting. I'd like to hear from some of the black members who may have personal experience with it or relatives who do.