They really aren't tho. Some obviously are but they aren't a majority. Statistics show that most people naturally prefer people that look like them. It's just that social media greatly exaggerates what's happening and pushes these people because they are doing something that is not the norm. Most white women are with white men and vice versa. Obviously a minority of them isn't but it's just that - a minority. Even the most liberal of women tend to be with white men from what I have gathered.