So what is the big deal about "interracial" marriage? We are all souls made in the image of Almighty God. In baptism, we are all brothers and sisters of Christ. Even St Paul made no distinction... So why should we? As long as we are united in the Faith, nothing else matters.
There is nothing morally wrong with it. But it can be used in ways to do damage. i.e. Jews taking over the world.
I personally would never date a white woman who has been with a black guy because there is the possibility that she might decide that she prefers black men for
biological/taxonomical/physical reasons. Plus I prefer white women. So if a white woman goes with a black guy then she is pretty much taken out of the dating pool for me at least. Now I have less options to choose from.
Not to mention, our culture and way of life is at stake because of interracial.
Those are just some personal reasons. There is a lot of reasons to be against it. Most people would not be willing to accept them however. They want everyone else to believe that there is no difference between the races etc. And those are the same people who are pro-interracial. Personally I just think these are white women who want people to accept them when they end up with a black guy. And black guys who want to upgrade by getting with a white woman.