Answer:

MONOGAMY

AnswerCrossword Clue
MONOGAMYSingular espousal?
MONOGAMYOne-man woman's practice
MONOGAMYOne-mate state
MONOGAMYHoped-for trait in a spouse
MONOGAMYMormon doctrine since 1890
MONOGAMYFaithful practice
MONOGAMYChallenge for a playboy
MONOGAMYPractice that isn't part of an open marriage