Dr. Jennifer Roback Morse vivisects the notion that getting the government out of the marriage business represents some kind of solution:

. . . .Now we can see what “getting the state out of marriage” likely means in actual practice. It means eliminating the default marriage contract, with these background conditions. We know that the state has already shown itself to be uninterested in enforcing sexual exclusivity and permanence. Social pressures to form stable unions are almost non-existent. Yet the “social safety net” for unmarried mothers and their children will not go away, and in fact would probably be strengthened if the government didn’t recognize marriage as such.
The most likely outcome, therefore, is that few people would even attempt to create a lifelong contract. The “prisoners’ dilemma” problem is at work here: it is publicly beneficial for society to have a norm of long-term marital stability, but it is in each couple’s private interests to write an escape clause for themselves into their own contract.
Would getting the state out of marriage make us freer? We can get a glimpse of the answer to this by looking at the impact of no-fault divorce. Presented to the public in the name of personal liberty, no-fault divorce has led to an increase in the power of the government over individual private lives. Family courts are one of the most intrusive institutions of the modern state, regulating how mothers and fathers spend their time and money. People under the jurisdiction of family courts can have virtually all of their private lives subject to its scrutiny. This is not an increase in freedom: it is an unprecedented insertion of the state into domestic matters.
Neither will an increase in “multi-partner fertility” (we won’t be able to call it “out-of-wedlock” childbearing any more) increase personal liberty. The state currently gets involved in regulating disputes between never-married parents, with all the same problems of intrusive family courts. Historically, the state’s attempts to make unmarried fathers to pay child support are much less successful than attempts to get divorced fathers to pay. And taxpayers will be on the hook for even greater expenditures for additional social services, since the outcomes for children are predictably dismal. Personal liberty will decrease, whether liberty is defined in terms of privacy or economics. . .