You could apply for naturalization now (3 months prior to the 3rd anniversary of your first green card) if you *continued to live together* with your U.S. citizen spouse. Since you have separated for over 6 months, the privilege of early filing is not available to you, and you have to wait another 2 years before filing for naturalization.
Answered on Oct 26th, 2016 at 7:30 PM