This scene takes place immediately following the Supreme Court decision that legalized gay marriage. If we think about the gay marriage market, a law that prevents gay marriage is essentially like a quota of 0, which leads to huge amounts of deadweight loss. As soon as the quota is removed/the law is changed, the lines at the courthouse are long as all of those previously prevented from marrying rush to get married.
See more: demand, efficiency, inefficiency, markets, quotas, role of government, supply, transaction barriers