I have a (beautiful) friend who is from Nigeria that I've found very attractive in many ways... I think the times I felt uncomfortable about her race were mainly when she "talked black" or when she acted like black Americans are oppressed by the evil white majority. Other than that, I personally just couldn't see myself having children with her... that would be really weird for me.

My recommendation as far as the comfort level goes... just act feminine and try not to bring up the race subject too often. If a guy doesn't see you as being different, you don't need to make him feel like he's different.