Marriage certificates of civil status only become public after 75 years. Also don't forget to check the marital attachments, Open Archives often provides links to this. Civil status records are always drawn up in duplicate: one goes to the municipality where the event took place and ends in the municipal or regional archive, the other goes through the court to the provincial archive (RHC).
This index contains 30,404,779 historical person listings.
The marriage certificates as made available online by North Holland Archives, Brabant Historical Information Centre, Gelders Archive, AlleFriezen, Historical Center Overijssel, Rotterdam City Archives, AlleGroningers, Regional Historic Center Limburg, State Archives of Belgium (Brussels), The Utrecht Archives, Municipal archive The Hague, Zeeland Archives, Regional Archives Dordrecht, Drenthe Archive, National Archives / Archives South Holland, Regional Archive Tilburg, West Brabant Archives, Heritage Leiden and environs, Regional Historic Centre Eindhoven, Regional archive Langstraat Heusden Altena, State Archives of Belgium (Mons), City archive Breda, Archive Delft, State Archives of Belgium (Ghent), RHC Rijnstreek en Lopikerwaard, Regional archive Voorne-Putten, Regional Archives Rivierenland, City Archives Enschede, Historical Archive Westland, Municipal archives of Venlo, Municipal Archive Borsele, Municipal archive Venray, Regional Archive Alkmaar, Municipal archive Schiedam, Regional History Center Vecht and Venen, State Archives Belgium (Hasselt), Rijckheyt, center for regional history, Municipality archive Alphen aan den Rijn, Hof van Twente municipality, City archive Zoetermeer, Municipal archive Ede, The Flevolands Archive, Municipal Archive Kerkrade, Municipal archive Hengelo, Municipality of Zederik, City of Lommel - Archive service, Municipal archive Wassenaar, Municipal archive Zaanstad, State Archives of Belgium (Antwerp-Beveren), Municipality of Oldenzaal, Municipal Archive Ommen-Hardenberg, National Archives Suriname, Archives De Domijnen Sittard-Geleen, Historic Centre Leeuwarden, Eemland Archive can be searched here.