When I was in the Army I knew a lot of Black soldiers that married German or Korean women. I also know a lot of White soldiers that married German or Korean women. The truth is that regardless of the race of the American soldier, these marriages were ALWAYS difficult.
In my experience, the problem was CULTURE not race. It is really hard for women born and raised in another country to come to the US and live. If you never lived anyplace else accept the US you simply will not understand how different it is living in another culture. I spent 3 years living in Germany, it is VERY different than being in the US. Everything from navigating health care in the US (which is an epic sh1t show) to having advertising in your face all the fvcking time.
When I first moved to Germany it was an adjustment that things were more expensive... but the tradeoff in Germany is no matter what service you paid for (painting, home maintenance, car repairs, et. al.) you got a quality product. You didn't have to worry about if you were taking your car to get fixed at a 'good' mechanic... you were going to get quality work... In the US, while things can be cheaper, you always have to struggle with making sure that you were getting quality work. Another thing I had to struggle with is operating hours from different businesses. In the US, if you want to get something to eat at 10PM, well you can find restaurants that are open... not in Germany... businesses are closed early and on Sundays... but in Germany, people have generous leave time to accommodate operating hours of businesses.
Another thing you notice is that you never see some junk car driving on the roads, because that is illegal. You would never seen some idiot driving with plastic sheets instead of windows. German pretty much follow the rules. A German woman moving to the US is going to struggle with commercials, billboards mucking up the environment, homeless people begging in the streets, people living in run down houses, the level of crime... the feeling that you always have to be on the look out for cons, keeping your hand on your wallet, wondering if you are going to get ripped off. Fighting with insurance companies.... It is these cultural differences that cause problems.
We have sub-cultures in the US, and if you are trying to date a chick that comes from a different sub-culture THIS is going to a bigger problem than skin color.