You don't have the right to lay your hands on a woman in order to "correct her mistakes". What is she, your maid? If you've had enough of her, break up with her. Be a man and path ways with her instead! Violence is resorting to new lows!
It depends on the couple, and it also depends on your spiritual standing. If you are religious or spiritual, then chances are you know what the Bible says about it... which is, pre-marital sex is wrong. So, it's relative!
White people aren't the only ones guilty of racism! Lots of black racists out there. I'm not a racist, but sometimes I let previously formed stereotypes color my perception of people before I meet them.