Adultery or Fornication results in a fine of $500 and/or 6 months in prison.

97-29-1. Adultery and fornication; unlawful cohabitation. If any man and woman shall unlawfully cohabit, whether in adultery or fornication, they shall be fined in any sum not more than five hundred dollars each, and imprisoned in the county jail not more than six months; and it shall not be necessary, to constitute the offense, that…

Adultery is illegal, but can only be punished upon a complaint by the affected husband or wife.

750.30 Adultery; punishment. Sec. 30. Punishment. Any person who shall commit adultery shall be guilty of a felony; and when the crime is committed between a married woman and a man who is unmarried, the man shall be guilty of adultery, and liable to the same punishment. History: 1931, Act 328, Eff. Sept. 18, 1931…

Unmarried couples may not commit “lewd acts” and live together in the same residence.

798.02 Lewd and lascivious behavior. If any man and woman, not being married to each other, lewdly and lasciviously associate and cohabit together, or if any man or woman, married or unmarried, engages in open and gross lewdness and lascivious behavior, they shall be guilty of a misdemeanor of the second degree, punishable as provided…