This is where you need to check, actual certificates Death Certificates often provide who their spouse was. In Australia it is recorded on the death cert. You may need to look at newspaper clippings, is there an obituary for either person. Or is the name recorded on a child's certificate. Is there a marriage announcement in the paper. What names are associated with Memorials or funeral notices.It takes a bit of investigating. The worse thing of course is that it is a completely different person and you need to start again.
Happy sleuthing, the end result is worth it.