Many thanks for finding this & taking the time to report it so clearly. I'll get it fixed in the next update.
Why? Must laws remain what they are in real life? Why not allow polygamous marriage? Sounds fun to me. Might as well make it a feature rather than squashing it.
I'm happy to add it back in later on, as an optional feature, if there's demand!
But I'll miss my polyamory ;~;
The next update lets you have lots of girlfriends all living together with you, so hopefully that'll help make up for it!
It is a shame polyamory is currently off the table, but for the sake of bug-fixing, I am glad it is being addressed.
