There is a fundamental difference between personal choices in marriage and the rules for engaging in commerce. Commercial activity is simply different than choices in your personal capacity.
Discriminate in your your personal capacity all you want. Don't date outside your race, don't associate with people you think are icky, don't marry someone you don't like for any reason in the world. [But if you deeply love someone for a host of reasons but don't want to marry them for the sole reason that they are black, then yes, you are a bigot.]
But if you want a license to engage in certain occupations, sell certain products, incorporate, deduct business expenses, use public roads in the pursuit of profits, or otherwise economically engage with society as a business, then society can establish rules for doing so. And they will - history is not on your side.