[nescience]

Relationships between members of different cultures can be fairly difficult; typically humans seek out members of similar cultural and socioeconomic backgrounds as partners in order to minimize these difficulties. As individuals are raised from childhood, they are socialized into their respective social and ethnic classifications which will support specific personality traits. When encountering someone who underwent a different socialization pattern, these distinct personality traits will generally result in various difficulties in the development of relationships.

That being said, most of the time, I don't feel that the cultural or social differences are more powerful than the interpersonal connections that can arise in the development of an intimate relationship. Often, these differences can even make for interesting conversation and chance to further develop the relationship. These cultural differences will, however, always create some amount of strain on the relationship; it's just that this strain can be overcome.

Personally, I've dated/married outside my social class and ethnic group several times, with mixed results. I'm American, white, and was raised in a semi-rural middle-class lily-white community. My ex-wife, also white (and part native American), was raised in a working class urban environment. We had radically different life experiences, which definitely caused strain in our marriage, but which we were definitely able to overcome (our divorce, I feel, had very little to do with our different social backgrounds). I've also dated a woman of Chinese descent, although American-born and socialized, and I felt that while we had interesting differences in our cultural makeup, generally the strain caused on our relationship by those differences, while present, was minimal and fairly irrelevant to the development of our relationship. However, in dating an African woman, who had only been in the country for a couple years but who had been fairly Americanized, I felt that the strain created by the vast differences in our socialization definitely caused enough problems that it made the relationship much more difficult and uncomfortable than I'm used to.

I don't know if this helps, but I thought it was an interesting topic. =) I didn't mention religious differences, which in addition to social and economic disparities, can also create its share of problems. Basically, though, in my experience: yes, cultural (and socioeconomic) differences do place a strain on relationships, albeit a surmountable strain. You mention that 2 of the 3 interracial relationships you've seen have ended up in divorce; I wouldn't give that too much consideration, however, as that's actually fairly close to current percentages, at least in America (if all of these relationships involved Americans, as the one you cited did--I couldn't really tell from the post).