Amusing confusion around Iberian wedding

[Norppis]

I'd like someone to explain me thematically what just happened in my game. Year 1480 or so, nation Castile.

I had a king Juan and heir Alfonso, both quite untalented and both as army leaders.
Event. Possible new heir, Isabella of Castile. I took her as new heir.
Few years later, Juan (0/1/1) abdicates to let more talented Isabella (5/6/5) rule.
Royal marriage with France. Isabella gains French king-consort.
They gain new child heir, Pedro.
A few years later, event Iberian wedding. Isabella marries Aragonian king (despite being apparently married already?) Personal union is formed.
And it turns out, all this time, Alfonso has been leading an army as a heir, despite two other heirs of throne having been there.

And I'm like, what just happened?

 

[Howl]

My take on this?
The french guy is literally a trophy husband. As in: She had him beheaded and mounted his head on a wall in the throne room.
Was Pedro born the day of the wedding? Then obviously the father is someone else. What are his stats? Could be the son of the devil...
Iberian Wedding: Now she also took over Aragon. Is the former king still in the game? If not, check the wall in the throne room, he might have taken a place next to the original husband.

Alfonso? We all know where his brain is at. He probably has not noticed (and no one told him) that he has been disinherited. Also people with these stats subbornly refuse to die in any case.

 

[Meglok]

Iberian politics at their best. This is almost as good as the actual history was.