Partnered Sims turn into siblings

Just had this problem too, with a same-sex couple, one of which has skillful sleep (though ive never once used it?) and it happened right after going into CAS. I'd gone into CAS multiple times before but it marked them as brothers only this most recent time. I had to roll back to a previous save to undo it, and now I'm paranoid it'll happen again if I go back into CAS. The whole reason I went into CAS was to edit their turn ons and turn offs (because romantic satisfaction is ANNOYING so I wanted all the romance styles to be turn-ons) and after I saved and exited CAS they were marked as siblings and couldn't romance at all. I only have the better butler mod from littlemssims and I don't think it's a mod issue since it's happening to console players too. It's ridiculous this hasn't been fixed yet. I recommend just saving before you go into CAS every time you do it just in case!