It wouldn't have to matter if they never married, if the legitimate heiress of Castile, Joanna, had succeeded her father, instead of Isabela, who was a half-sister. Joanna married the King of Portugal, and could have merged the crowns of Portugal and Castile, instead of Castile and Aragon.
I presume you mean Joana la Beltraneja. In that case, wouldn't the guy who married Isabel try to gain the throne anyway, given the questions about Joana's paternity? If Isabel doesn't marry Fernando - and she obviously isn't going to marry a member of the Portuguese royal family - then who does she marry? A Castilian nobleman like the Duke of Alba or Medina Sidonia, or a relative of the French King, or someone with no ability to push for her claim to the throne?
I don't know how strong Navarre was at the time
She was betrothed to the Duke of Guyenne, a Valois perhaps that marriage could push through.I presume you mean Joana la Beltraneja. In that case, wouldn't the guy who married Isabel try to gain the throne anyway, given the questions about Joana's paternity? If Isabel doesn't marry Fernando - and she obviously isn't going to marry a member of the Portuguese royal family - then who does she marry? A Castilian nobleman like the Duke of Alba or Medina Sidonia, or a relative of the French King, or someone with no ability to push for her claim to the throne?
It wouldn't have to matter if they never married, if the legitimate heiress of Castile, Joanna, had succeeded her father, instead of Isabela, who was a half-sister. Joanna married the King of Portugal, and could have merged the crowns of Portugal and Castile, instead of Castile and Aragon. Castile was already outward-looking, as was Portugal, and instead of dividing the New World between them, the united kingdom would have taken practically the whole thing. Aragon would have stayed a Mediterranean power and could have become even more involved in Italian (and perhaps North African) affairs.