Found this thread on 'Similar Threads' section on a thread I was posting on. I don't know if I'm surprised or not surprised that it went unanswered because diversity in own culture isn't acknowledged much, least of all on mumsnet, except within those cultures where you'll find diversity.
For example in Africa, there are many ethnicities in each country, therefore one African country may have different cultures and languages, but to the outside eye, they're all the same.
It's why it's reductive to talk about 'Africa' and not specify where in Africa bar for privacy reasons, as if every African is the same.
It's equally as reductive to talk about race (White, Black, Asian, etc) as if every White, Black or Asian belong to the same ethnic group and behave the same, let alone think the same way.
It really isn't a complex issue but can be for people who haven't the experience or those who're so blinkered by their one identity experience that they either refuse or are unable to see diverse identities.
You can have a lot in common with someone of a different 'race' to you if you have the same cultural reference and vice versa, like your post confirms, OP. (Wonder if you're still here). You don't have to be in a relationship with someone if you don't have much or the important things in common. It doesn't matter if you're from the same place or the same 'race'. Problems will continue to surface if you do.