Most of my list is already posted here but I need to add some matches
https://www.alternatehistory.com/fo...that-never-sailed.463396/page-2#post-18583951
Maximilian of Austria (OTL Emperor of Mexico) and Marie Amelie of Brazil
Napoleon II and Princess Sophia of Bavaria (yes the OTL mother of Franz Joseph and Maximilian)
Lorenzo de’ Medici, Duke of Urbino and Bona Sforza (is a good match and would take away many troubles)
Sigmund the Old of Poland and Katharina of Mecklenburg
Philip of Burgundy and Anne of Brittany (but need a lot of differences from OTL for working)
Henry V of England and Katherine of Pomerania (much better keeping him awa6 from that Valois obsession and giving him an older son as heir)
Emperor Frederick III and Margaret of Anjou (and I would like it more if not for the fact who Maximilian I will not exist here)
Charles I of England and Anne of Austria-Spain (would be a better match than OTL for both and wil, be possible if Henry IV will survive)
Charles I of England and Maria Anna/Cäcilie Renata of Austria
Ferdinand jr of Austria (son of Emperor Ferdinand I) and Isabella of Poland (she is ten years older than him but them having kids and Sigismund Augustus with OTL like troubles would give us a stable and indipendent Habsburg Poland (well you need also to prevent the extinction of the main line of the House of Austria)...
Ferdinand jr of Austria (son of Emperor Ferdinand I) and Mary I of England (uncle Karl V will need to give him Netherlands raising it as Kingdom for concludeing the match but if Philip is not available will likely do it as would be better than marrying Mary himself or trying to force his brother Ferdinand to do it)
Emperor Matthias and Isabella Clara Eugenia of Spain
Archduke Ernest of Austria and Isabella Clara Eugenia of Spain
Saint Casimir of Poland and Kunigunde of Austria
John Albert of Poland and Germaine of Foix
Emperor Matthias and Elizabeth Stuart of England (the OTL Winter Queen not her namesake niece)
Emperor Ferdinand II and Elizabeth Stuart of England (again the OTL Winter Queen... really unlikely but would be fun)
and for the list of couple married who I consider failed ship
Sigismund August of Poland and Barbara Radziwiłł (because they deserved a longer wedding)
Albert of Austria and Isabella Clara Eugenia of Spain (they deserved to marry earlier and having a longer wedding with heirs)