h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Some years ago I met an elderly gentleman who fought in the war. At an ealy stage he was taken captive abroad however this information was never transmitted back to the UK and he was noted as Dead - Lost in Battle. Before he went off to fight he married, hence his wife was officially a widow and in the course of the war married another man and started a family. After the war her "dead" husband returned !! Why I raise this now is that during the period 1945-59 I am sure that this must have happened several times, and it makes me think about how difficult it must have been for the three people involved, what was the legal and moral actions that should be taken ??