Your result
Spain — Marriage
Not eligible
The marriage route is closed to you, and Spanish law is unusually explicit about it.
The reduced one-year residence requirement is available to someone who at the time of applying has been married to a Spanish citizen for a year and is not separated, either legally or in fact. A divorce ends it. So does a separation that has not been through a court, because the statute catches de facto separation as well as legal separation — living apart is enough, and applications have failed on exactly that point.
If you are separated but not divorced and there is a realistic prospect of reconciliation, this is worth advice rather than assumption, because the test is applied at the date of application rather than for the whole of the preceding year.
What is not closed is everything else. If you have been living in Spain under a residence permit, that time counts towards ordinary naturalisation — ten years for most nationalities, but only two if you are a national of a Latin American country, Andorra, Portugal, the Philippines or Equatorial Guinea, or if you have Sephardic ancestry. Many people in your position are much closer to the two-year threshold than they expect.
It is also worth checking what happens to your residence card. Residence rights held as the family member of a Spanish or EU citizen can survive a divorce in defined circumstances, particularly where the marriage lasted a certain time or there are children — that is the more urgent question, and it is worth taking advice on quickly rather than waiting.