Is the suitor sinful or burdened with guilt if he does not marry the girl he wishes to marry, and whose family refuses to allow him to marry her because of her skin color, even though the girl is religious and of good character?

A father does not have the right to prevent his son from marrying a certain girl unless there is a legitimate reason. If the father insists on preventing him, the son commits no sin by marrying without his father's consent, and this is not considered an act of disobedience. A heart becoming attached to a girl is not a sin, as long as it does not lead to something forbidden or prevent an obligation.