As we have been engaged for about 15 years, Carakeel and myself are possibly getting married this year or next. However Carakeel can not find divorce papers after living in various places in Europe and a few moves in the UK, (divorced in Germany many years ago and the German government office cant find the papers either) We believe that her ex husband died quite a few years ago. Does she have to prove that he died before we wed if we cannot locate the divorce papers. The divorce definitely happened, I'm sure of that.
I'm not sure of the mechanism but it is possible to have someone declared dead. A friend of mine (many years ago) wanted to marry a lady whose husband had disappeared many years before and was believed to be dead. I think a 7-year period since the believed death is the significant time.
I would suggest that if you can offer proof that you have exhausted all reasonable attempts to prove the divorce and or death of a previous partner, that it is unlikely that any objection will be raised.
That said, a death will more likely be recorded in a retrievable form - have a chat with the Citizens Advice Bureau on where to start looking.
I’m no expert in this area, but given the number of people who enter into bigamist marriages – I would think that there is no requirement to prove that you are single/divorced/widowed in order to marry. Should it prove to be that your intended never divorced and that her ex is still alive, then she will be entering into an illegal marriage – which may or may not come to light at some later date.
has she tried googling his name? that's how I found out that my brother in law had died and where. After that it was easy enough to get a death certificate from that country.