Take the United States of America for example. Black men are seen as vicious sex beasts with huge penises that constantly rape their black women and seek out white girls to satisfy their animal urges. Likewise Black women are seen as irresistible whores who couldn't possibly have the brainpower to be traumatized by rape, because they always want sex like their black brothers. The sexualization of black people in America, while not specific to black and white people, has led to widescale castration and lynching of black men who were thought to be seeking out a white woman. As well as widescale rape of black women by white people above them, to spite these same black men. But once black women became "Easy" they became worthless. Same way prostitutes are hated by society and men who sleep with one are seen as losers; black women became the "Easy" way to get laid, and thus white men who enter relationships with them are pathetic for not being able to get a white woman as a lover.
This mentality ingrained itself into American society which is why we now have life imitating art today more than in the past, compared to black man white woman relationships becoming less taboo over the years. In addition, black communities are usually aware of their sexualized past, which is why a notable amount of black people despise these relationships, but may be less so toward the inverse.
