The only real problem facing unmarried couples with regard to health insurance is the other partner. A family plan means just that family. Childbirth and children can still be covered under a plan for either partner. It’s that extra person in the house that is so difficult to define. When is the other person a partner? When you say they are? Think of the potential for unmitigated fraud.
Anyone who had a friend could say they were partners to get covered on a policy. What if that “partner” needed a liver or heart transplant? How many people would be able to be paid a sum of money to lie about the relationship to get coverage for someone who isn’t insurable under private plans? This has to be a nightmare for insurance companies. Already people fake marriages for this type of thing or to gain citizenship rights.
I have sympathy for legitimate couples who are struggling to find a solution to this dilemma. Without some sort of contractual agreement to protect the insurance companies from fraud, it is a problem that isn’t likely to go away soon.
From the couple’s perspective, whatever reasons they have for not just getting married will probably get in the way of a contract. The exception to this might be same sex couples who choose to establish a life partner contract with each other. With a contract in hand, some law should be able to be crafted to allow for these legally committed partners to get insurance coverage. Obviously, the current societal bias against same-sex unions will stand in the way of passing legislation to make this happen.
Because any law that sanctions unmarried contractual unions would give equal rights to heterosexual and homosexual couples, both will be left to continue the battle. The courts really have no basis in law to compel the insurers to extend the desired coverage.
It is possible that the companies themselves could unilaterally decide to honor a legally binding contract in the same way as a marriage license. I would not hold my breath waiting for this to happen.