The way I see it, when it comes to a romantic or sexual partner, that's the one area where you are allowed to be discriminatory, for various compatibility reasons. You might call that way of thinking problematic or whatever, but I think it'd be hard to make a relationship work where one party either doesn't find the other attractive for whatever arbitrary reason or if they have nothing in common interest-wise. Some people have hangups about stupid things, or very specific interests when it comes to sexuality. (also there's the fact that if a person actually is prejudiced against a certain ethnicity/orientation/what-have-you for whatever reason, people who are part of that ethnicity/whatever don't want to be dating said person anyway, I'd think.