Catherine of Navarre can marry an Armagnac, however, Louis the Spider hates the Armagnacs very much..
Yeah, but by the time of Catherine's OTL marriage in 1484, the Spider King was dead, and his daughter was in control of the regency.
Catherine of Navarre, in this scenario, could marry Charles, Count of Angouleme.
An interesting match to be sure, but how would the factions (Agromontese vs Beaumontese) at the Navarrese court feel about this? And would Angoulême be in any more of a position to help Catherine fight than say the Albrets of OTL? AFAIR, the Angoulêmes possessed the smallest patrimony of the French royals (when placed alongside the Orléans, the Anjous and the Bourgognes), so it wasn't until they were next in line to the throne and Louise of Savoy was scheming for her son and daughter, that anyone was actually concerned about them.