By law, if a man promises to marry an unmarried woman, the marriage must take place.

Title 16 – Crimes and Offenses
CHAPTER 15.
OFFENSES AGAINST MORALITY AND DECENCY
ARTICLE 1.
MISCELLANEOUS OFFENSES

SECTION 16-15-50. Seduction under promise of marriage.

A male over the age of sixteen years who by means of deception and promise of marriage seduces an unmarried woman in this State is guilty of a misdemeanor and, upon conviction, must be fined at the discretion of the court or imprisoned not more than one year. There must not be a conviction under this section on the uncorroborated testimony of the woman upon whom the seduction is charged, and no conviction if at trial it is proved that the woman was at the time of the alleged offense lewd and unchaste. If the defendant in any action brought under this section contracts marriage with the woman, either before or after the conviction, further proceedings of this section are stayed.