If the wife survived when the husband dies, be certain to look through all the estate and probate records for clues about subsequent marriages by the widow. In some cases, she may be listed as "Barbara, late wife of Henry Smith, deceased." In other cases, her new marital status may not be stated so clearly. The widow could be listed on virtually any document in the estate papers simply with a new last name, with no mention of the husband.
And if the wife appears in initial papers settling her deceased husband's estate and a man, whose not a known blood relative of the widow or deceased husband, suddenly "appears" in the records--check him out. There's a chance he is the new husband, just with the relationship not stated.