Purpose: We aimed to characterize couple-level private insurance coverage among same-sex and different-sex couples before and after the Obergefell v. Hodges (OvH) decision legalizing same-sex marriage in the United States. Methods: National Health Interview Survey data were obtained for 2012-2014 (pre-OvH) and 2016-2018 (post-OvH). Coresiding couples with both partners aged 27-64 years and at least one having private insurance were included. Couple-level coverage was private for both; private for one, other coverage for another; and private for one, none for another. Secondary analysis examined whether either partner was covered by the policy of a family member in the household (partner/spouse coverage). Results: The analysis included 69,251 couples. Ninety percent had private coverage for both partners; 5% had one partner with other coverage; and 5% had one partner uninsured. The share of same-sex couples with both partners having private coverage increased from 79% to 88% after OvH (p = 0.003), whereas it remained at 90% among different-sex couples. In multivariable analysis, this increase was explained by the increase in legal marriage post-OvH. Among unmarried same-sex couples where both partners had private coverage, the odds of one partner being covered by another's policy decreased by 61% after OvH (95% confidence interval: 35%-76%). Conclusion: OvH was associated with greater access to private insurance for same-sex couples and lower risk that one partner would have private insurance while another would be uninsured. Yet, partners in unmarried same-sex couples became less likely to share the same private policy.