It doesn't matter if you were married in a country other than that of your nationality/citizenship. What counts is that you are now married. You can no longer check "single" in either a U.S., Dutch or Patagonian tax return document (or any other document).
I hope this helps.
Behar Intl. Counsel 619.234.5962 Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.
The truth is that you are married.
Please be advised my answers to questions does not constitute legal advise and you should not rely on it, due to the fact that we have never met, I have not been aprised of the facts in you case nor have I reviewed any documents.
I say you are married as you are legally married in the place you reside. it is likely that if you came to any state in this country, your marriage would be respected. If you were married as of the last day of the year, you can file Married Filing Jointly or Married Filing Separately. But keep in mind, you must file as a US citizen.