What happens to the 2nd wife if I stop being polygamous in CK3

I am playing as the High King of Ireland, who, as an Insular Christian, is required to have 3 wives if I don't want a piety generation penalty.

When my half-sister died, it pushed me into a mental break, and I was given a choice where one of the options was to convert to Paulicianism, another Christian sect. The big difference though, is that Paulicans are monogamous.

If I make the switch, what happens to my existing marriages? Do they get annulled? Stick around? (but don't do it again, buster!) Is this true even when switching to a faith that doesn't allow divorces?

I wasn't willing to risk it (and am playing Ironman) so I did not find out.

Best Answer

I just tested this as an Ash'ari (Muslim) ruler converting to Catholicism.

This is what happened to my 3 secondary wives:

I received 3 messages which read "Spouse Invalid - Your new Faith's beliefs mean that [name] is no longer your spouse".
They became regular courtiers in my court.
They did not change their religions (but my primary wife didn't either)
They did not have an opinion penalty for being divorced (just one for me being an Evil [sic] Catholic).
A couple days later, one of my ex-wives informed me that she is pregnant and that "Since we were married when this child was conceived, there is no stain of bastardy; when the babe is born it will be known as your legitimate offspring".

So TL;DR: Converting to a monogamous religion will get you a "free" divorce from your secondary wives without any of the usual restrictions, costs or penalties.