There is a question about whether dating - knowing one does not intend to marry the other person - 'is sin', but it has nothing to do with the colours of those dating.
Paul Washer, one of the preachers featured here on SI, has several sermons on this matter. He himself is white, married to someone who is not white.
There are many examples in scripture of intermarriage between people of different colours of skin. Jewishness did not distinguish against colour of skin. There were Jews of all colours. I think this speaks for itself.
Numbers 12:1 And Miriam and Aaron spake against Moses because of the Ethiopian woman whom he had married: for he had married an Ethiopian woman. {Ethiopian: or, Cushite}
King David is identified as the opposite (colour of the Ethopian) 1 Samuel 16:12 And he sent, and brought him [David] in. Now he [was] ruddy, [and] withal of a beautiful countenance, and goodly to look to. And the LORD said, Arise, anoint him: for this [is] he.'
{of a...: Heb. fair of eyes} So, David had a rosy complexion and blue eyes?
1 Samuel 17:42 And when the Philistine looked about, and saw David, he disdained him: for he was [but] a youth, and ruddy, and of a fair countenance.'
David had several wives, probably all of whom were not as 'fair' as himself, since he was remarkably fair.
After David had taken Bathsheba, and God was speaking to him about it, God told David that if he'd wanted another wife, he only needed to ask God for her. This implies God's approval of all his previous wives, and that David had taken them with God's approval.