Game freezes when getting married

So I had this couple, and one of the Sims was a spellcaster while the other was not. The spellcaster Sim was immortal, their partner wasn't, and when the non-spellcaster Sim died, they reincarnated as their own great-grandchild.

Prior to the most recent patch, the reincarnated Sim and their great-grandparent/old spouse had recovered their memories of being soulmates and remarried. Upon loading this save post-patch, their marriage was gone, though their romantic feelings and memories of being soulmates weren't. When I tried to marry them again, the game froze. Or rather, the UI still worked and all, but the game clock was not advancing, and all Sims were stuck in whatever animation they'd been previously in.

I assume what's happening here is that the game is entering an infinite loop of trying to recalculate the family tree when a Sim is married to their own great-grandparent. And while my game is modded, I don't think this particular feature required a mod to work? As far as I know, reincarnation and restoring soulmate memories and all that are a base Life & Death game mechanic.