Partnered Sims turning into family members

I've had this issue in two separate saves now where my married Sims randomly turn into siblings. Both times, the couple in question were both male. I'm wondering if there is a solution on the horizon for this? It is so frustrating because the few fixes online that others have suggested don't seem to work at all. I've tried using MC command center to edit relationships, etc. and nothing seems to work. Does anyone else have any suggestions?