Sexual Relationships 
Sexual Health 
For a lot of white women being with a black guy often falls into one of these categories:
1. Jungle fever - The fetish for black men. In fact one of the biggest sex tourist places in world is Jamaica where a lot of white women go to get fucked by black men. Now, the drive for this fetish often spark by the belief that black men are well hung.
3. Another reason for picking black men is cross it off on their bucket list.
4. Wanting to bang stereotype. Many black guys have experience this where they get all the signals from a white woman to approach but then present themselves as articulate, intelligent bookworm kind of guy and not the stereotypical player, cool guy, thug, b-ball player that the media portrays black men as. What happens afterward is the woman loses complete attraction for him because he is not a "TRUE" black guy but what you'd call an UNCLE TOM.
For black men getting with white women often comes about because of media influence portraying Caucasian features and white women as the ideal beauty. So many black men chase white women for status. We often see incite into status white women play when many black celebs dump their black girlfriend for white women.
Another reason is many black men are self hating of their race and want their kids to look more "beautiful" by getting Caucasian features. I've actual come across several happy married blacks who insulate or outright state that their reason for getting with a white woman was because they wanted their kids to be more attractive.
And self hate starts from early age with kids.
What Girls & Guys Said
10 19If say most interracial relationships are happening in interracial neighborhoods. The people see each other as "their kind" because they grew up in a diverse community.
Most definitely
Not usually the case but some.
As you stated it is said that most black men are hung. It isn't the only reason but it is part if the mystique although a majority of white women say Size doesn't matter but it really does they just don't want to be honest maybe they feel it makes them shallow. Not sure. I am sure most have thought about a guy they like or statred dating size crossed their mind at one point but they won't admit it.
I believe that is true more often than not. That's probably why those relationships generally don't last as long. Marriage statistics has that as one of the more unstable relationships out there with many other interracial marriages.
The only exception is black women/white men and I don't think they have nearly as much lust thrusting them together so they are more stable.