Are you legally married if your marriage license was never filed or even signed?

Question Details:

My friend got married and had a wedding ceremony a few years ago, but her and her husband separated 10/09. No one signed the marriage license - not her, her husband, or the pastor who performed the ceremony. So the license was never filed and she did not change her name. They did file married on their taxes however. So we were both wondering, since they never filed a marriage license but did file married on their taxes, would they need to get a divorce? Important Notice