Oh they could work too, it's just that they don't have the same royal history in England... Thank you so much for your input!
Ulster has a lot of royal history, but being an Earldom was used as secondary title by its holders (it came from Elizabeth de Burgh and had belonged to her heirs until Edward IV’s ascension)
Chapter 134, May 1524
Ribeira Palace, Kingdom of Portugal, May 1524

It was a stormy day, the gusts of wind pushing the rain against the windows of the palace. With her hair under her widow’s veil, Catalina of Aragon sat in her armchair, marveling at how the wind and water moved. The Lord shapes our world in mysterious ways…

She heard some voices outside the door to her chambers, but she paid them no mind. Maria wouldn’t be back from her Catalan lesson for several more hours, the bright girl had already mastered Castilian, in part thanks to being around her mother’s household, but also thanks to a keen intelligence that was already becoming obvious to all. Still thinking of this she relaxed, enraptured by the sight in front of her.

Finally, her attention was pulled away when her chamberlain, Vincente de Alpoim announced,”His Majesty King Joao!”

Looking over her shoulder, the woman saw her nephew, not dressed in black as he had been in the months prior. No, instead only his cap was black, sporting a tan jacket and matching trousers. He looked happy too, truly happy, not the mask that he had usually worn to make his courtiers feel at ease.

“You seem unusually happy.” The Dowager observed

The King moved to take a seat in the corner of the room, smiling,”Yes, it’s Catarina.”

“She is with child again?” Catalina asked

Joao nodded,”Yes it would seem so.”

“Good.” Catalina murmured,”Do make sure that Catarina takes to her lying in early, she may not like being cooped up in her rooms longer, but it will mean the child will be healthier.”

“Of course.” The King of Portugal agreed,”But you know how stubborn she can be sometimes.”

“Then tell her that her aunt and mother wish her to do so.” Catalina replied sipping from her cup of wine

“Is that not a lie?” Joao asked

The Dowager Queen shook her head,” No, it is mere misdirection, besides, if Juana were here she’d surely make her do so. So long as she and the baby are healthy the means don’t matter.”

“Thank you, aunt.” King Joao replied,”I know that I can always count on you for sage advice.”

Catalina of Aragon looked to her nephew and shrugged,“It’s nothing dear, I simply want what is best for my family, it’s all that I’ve ever wanted.”