Infidelity - breach of the expectation of sexual exclusivity.
West uses the term to emphasize the concept (common in polyamory) that one can be faithful to one's commitments without those commitments including sexual exclusivity.
At the start of my current relationship, I made it clear that sexual exclusivity was important to me.
They still love each other, but the felt necessity of sexual exclusivity has become a thing of the past.
People who identify as polyamorous typically reject the view that sexual and relational exclusivity are necessary for deep, committed, long-term loving relationships.
Polyamorists generally base definitions of commitment on considerations other than sexual exclusivity, e.g. "trust and honesty" or "growing old together".
He said that he believed that monogamy or sexual exclusivity was not a requirement for a valid Christian marriage.
Competition among women may be bound to advertising ones beauty and upholding a virtuous reputation for sexual exclusivity as long as demand is high.
Their commitment to one another and their sexual exclusivity are unquestioned, as is their devotion to the children some of them have reared.
Elswyth and Beebe had an open marriage, in which neither expected sexual exclusivity from the other so long as their life together was not damaged.