Why do men get mad when a women of there race dates outside of it. But its ok for them to?

I'm white. And I really only date white, but I should be able to date outside of my race without being slandered by the males in my race. I've never had this happen to me personally. But a friend of mine dated a black guy once and she was out casted by everyone who she thought loved except for me. Her dad through her out, her white male friends stopped speaking to her, and ex boyfriends called her a trader and sell out. I've seen and heard this happen to black women as well for dating a white man.