UPDATE: REPEALED in 2014, 44:1, effective January 1, 2015
Thanks, Rep. O’Flaherty and Rep. C. McGuire!
Adultery is punishable in New Hampshire as a class B misdemeanor crime:
CHAPTER 645 PUBLIC INDECENCY
Section 645:3 Adultery. – A person is guilty of a class B misdemeanor if, being a married person, he engages in sexual intercourse with another not his spouse or, being unmarried, engages in sexual intercourse with another known by him to be married.