Sex and relationships tend to be a very touchy subject, especially with the influence of religious dogma. Societal expectations in the U.S. on how many partners one should have, how long a relationship is supposed to last, and the ever popular gender roles are primarily informed by Christian tenets of morality.
The Association for Humanistic Rabbis released a statement in 2018 outlining the Humanistic Jewish stance on sexual ethics. As Humanists, the most important factor of relationships should always be consent. Monogamy, polyamory, and any other relationship configurations are valued as valid as long as all partners are consenting adults.
The following videos are from presentations on October 26, 2018 and November 9, 2018, respectively, by Rabbi Jeffrey Falick at the Birmingham Temple (now the Congregation for Humanistic Judaism of Metro Detroit) in Farmington Hills, Michigan, discussing this statement as well as the book Sex at Dawn: How We Mate, Why We Stray, and What it Means for Modern Relationships.