Many white women hate it when white guys date Asian girls. Many white guys hate it when white girls date black guys. Many black girls hate it when black guys date white girls.
It's simply evolutionary. You don't like it when a member of the opposite sex is attracted to a group to which you don't feel you belong. Even more so when you see that girl/guy as part of your group.
Once had a black coworker who had two, if not three, white girls pregnant at the same time. THAT bothered me, probably in the sense you are talking about. Felt like he was doing it to spite white guys like me, and didn't give a rat's ass about the kids he was making.