One of the reasons more progress hasn't been made in the effort to get employers - at least taxpayer-funded employers - to provide domestic partner benefits to employees is that proponents of domestic partner benefits have allowed this to become a debate over whether or not unmarried people should cohabit or whether homosexuals will spend eternity in hell.
Arguing about fornication and homosexuality obscures the real issue: employers who offer healthcare benefits to married employees that are not offered to single employees are discriminating against single people.
Let me show you how clear the nature of the real issue becomes when we don't know the sexual orientation or the living arrangement of the single person involved:
Two young, male accountants report for their first day on the job. Both men go to HR where they fill out new hire forms including healthcare insurance forms.
The married man is offered a valuable benefit that the single man is not offered: the opportunity to put other people on the employer health plan.
The single man is not offered this valuable benefit.
Categorically, this is discrimination against single people. The inequity is undeniable. Whether or not this inequity is illegal may depend on whether the employer is tax-supported and is a matter for courts to decide, but, illegal or not, it's an inequity. Everybody would recognize the inequity for what it is if employers were offering, say, free food to married employees but not to single employees or if employers were issuing free gasoline cards to married employees but not to single employees, but because this whole "domestic partner benefits" debate often comes up in the context of same sex partners or people who are living together without benefit of marriage, the true nature of this inequity gets obscured by the red herring issues of whether or not the Bible condemns gay people or whether or not adult men and women who aren't married to each other should live together.
It seems to me that there are at least three ways employers can rectify this inequity: One possibility is to simply stop offering to insure non-employees. Under this arrangement, the two accountants in my example would be offered identical employer healthcare benefits, that is, the two accountants would be offered healthcare but neither would be offered the opportunity to include someone else on the employer health plan.
Another way employers can offer equivalent healthcare benefits to all employees is to allow each employee to put the same specified number of people on the plan regardless of their relationship to the employee by whose plan they are covered.
Finally, employers could simply stop offering healthcare benefits.
People on both sides of the domestic partner benefits argument can say and think what they want to about homosexuality and fornication but the fact remains that when employers offer their married employees a healthcare benefit of greater value than the benefit offered to single employees, they are discriminating against single people regardless of their sexual orientation or living arrangement - and this is how the debate should be framed.
Unless the US gets universal, single-payer healthcare that renders this whole debate moot, I think the day will come when some clever lawyer will successfully argue that when taxpayer supported employers like state colleges offer better and more valuable benefits packages to their married employees than they do to their unmarried employees, they are guilty of discrimination against single people.