A man's wife, whom he has been separated for several years is suing?
I am not a family lawyer, but I have had two friends who managed to divorce their wives from much earlier marriages despite the fact that they couldnt even find their former spouses to serve them. In both cases they married young, separated, went their different ways and eventually left the country and lost touch. They then later wanted to remarry, but had the lingering problem that they were still technically married to their former spouse. I am not quite sure how it works, but they were able to petition the courts for divorce, some type of substituted service was made and the earlier marriage was dissolved (presumably despite the former wife never knowing about it - although who knows, she may have dissolved it herself in another court and never told them). There was no order beyond the dissolution of the marriage - no orders for maintenance or division of assets. So, it seems that in some jurisdictions at least, it can certainly be done.