So then... — Better, So then he that gives his daughter in marriage does well, and (not “but”) he that giveth her not shall do better. It is worth noticing how, in the case of the one who gives his daughter in marriage, we have the present tense “does well” — as if the good he did began and ended there; and, in the other case, the future “shall do” (in 1 Corinthians 7:37 also) — the good result of his action continuing while the girl remains with her parent. This passage clearly shows how St. Paul has not been contrasting right and wrong: but comparative degrees of what is expedient.
All throughout this passage the Apostle takes for granted the absolute control of the parent over the child, in accordance with the principles of both Greek and Jewish jurisprudence. Hence, no advice is given to the young maiden herself, but only to her father.