[Dr. Sivana]

It takes a truly powerful religious faith and practice to keep that under control, such as that of Isabella of Castile, who could and did rule her court religiously.

And even she couldn't control King Ferdinand.

[buwaya]

She did, repeatedly. It was tacitly understood that she was the senior partner.
There was one case during the campaign of Granada, when Fernando wanted to hare off to fight the French (France and Aragon had endless border disputes). Fernando stayed.