monogamist

noun

1. A person who practices monogamy.

   “I maintained with Whiston, that it was unlawful for a priest of the church of England, after the death of his first wife, to take a second, or to express it in one word, I valued myself upon being a strict monogamist.”

   “Suppose, for example, that if polygamy were legal, 10 percent of adult men would take an average of three wives apiece and that all remaining marriages would be monogamous. Among aspiring monogamists, there would then be nine men for every seven women.”