When reading your post, I couldn't help but think of Leon M. Bazile, the trial judge in Loving v. Virginia, who said:
"Almighty God created the races white, black, yellow, malay and red, and he placed them on separate continents. And, but for the interference with his arrangement, there would be no cause for such [interracial] marriage. The fact that he separated the races shows that he did not intend for the races to mix."
This rationale was used to de-legitimize an interracial marriage half a century ago. And to be fair, you didn't say this. But here's what's similar: since you had no rational way of explaining your preference, you appealed to nature, to chemistry, to unknown bugaboos that take over when it hurts our heads too much to reexamine the assumptions of our lives - in order to absolve you from responsibility, and to distance yourself from the role you play in the oppression of others.
After all, in the words of poet Andrea Gibson, privilege is not having to think about it.
Anonymous, if you really want to absolve yourself, stop defending systems that help you and hurt others. Research them. Expose them. Then, fight against them.
It's only by trying to change the system that you will truly come to understand it. If you take nothing else away from this post, understand that when bigcockjohnny89 responds to you instantly on Grindr, it is because he's accustomed to associating beauty with whiteness - because our dominant culture is white. It takes more effort for your black friend to get attention because we aren't used to seeing blackness as equally beautiful.
This dynamic doesn't make you racist. Defending it and allowing yourself to benefit from this system of romantic advantage without challenging it makes you a racist.