#extramarital_sex__free_love  sexual intercourse between individuals who are not married to one another
  supertype:  unlawful_carnal_knowledge__criminal_congress  forbidden or tabu sexual intercourse between individuals
  subtype:  adultery__criminal_conversation__fornication  extramarital sex that willfully and maliciously interferes with marriage relations; "adultery is often cited as grounds for divorce"
  subtype:  fornication  voluntary sexual intercourse between persons not married to each other

No statement uses or specializes extramarital_sex; click here to add one.