Matt Barber and Mat Staver of Liberty Counsel warned this week that gay marriage affects the marriages of heterosexual couples by making them less monogamous.

On the group's Faith and Freedom radio show, Barber and Staver were discussing the Family Research Council's (FRC) list of arguments against marriage equality, titled Ten Arguments from Social Science Against Same-Sex Marriage.

At number six is “same-sex 'marriage' would undercut the norm of sexual fidelity within marriage.”

Barber and Staver cites quotes from gay writers Andrew Sullivan and Dan Savage to assert that gay male couples are more likely to have open relationships.

“You start doing that in a marriage relationship with a man and a woman and the woman's just not going to do it,” Staver said.

Barber added: “We know that women serve to domesticate men. That's not an opinion. That's the social science that women ultimately bring men into their role as father, as provider, and protector for the household and they domesticate men and that lends itself toward monogamy.”

Writing at, Kyle Mantyla responded: “There are plenty of straight couples, of course, who engage in open relationships. So what any of this has to do with gay marriage is anybody's guess.”