I theorized this before. I think the reason is white people are the dominant race in America by population. White guys are not going to come at each other over who they date, and black people don’t shame black women as much when they date out as they do black men. But the white (dominant) population will attack anyone dating their women.
So with WM/BW, you’re not getting static from the black community and you’re not getting static from the white community because they’re not losing their own women, you as a white guy are taking some other group’s woman. You might have some racists but it’s not as forceful as it would be the other way around. Now if it’s a black man and a white broad, black women gonna hate you for “turning your back” on them, black men gonna call you a sellout, and white men gonna call her a mud shark. There’s also the unequal power balance of black men being at the mercy of the white woman switching up on you with police/court system, etc. which is a weird dynamic for your woman to have over you. Then going back to WM/BW, I also think there’s some element of black women letting some things go for white men that they wouldn’t let go for a black man because they want to be in what they feel is the WW’s position in society.