i guess because white men raped black women on the plantation, they raped and mutilated their bodies, cut live babies out of their pregnant bellies, burned them alive, whipped them senseless and enslaved the offspring that they sired with them. Their bi-racial offspring just became a lighter skinned underclass. Then the white gov't sought to destroy the Black family through biological warfare (man-made diseases), through lynching Black men and women (now they just throw young Black men in jail), and keeping the Black men out of many sectors of employment. Also the White controlled media defined beauty in America as a blonde blue eyed woman. NOT a sexy, brown skinned, braided, afro'd Black woman. And then look what happened. Black woman started wearing Blonde weaves and green contacts. Just look at Lil Kim. So if White men respect and honor Black women so much, why has he degraded and disrespected Black women for so many centuries?
I don't think that Black guys sit there and think of all of things that i mentioned when they see a Black woman with a White man. But I think some Black men, they just know something is not right about it. They have a vague awareness of the injustice that Black women have suffered at the hands of White men historically and currently.
I don't know how your friend justifies his dating outside of his race, but that would be an interesting conversation to have.