Marriage Cheating

Let me say that I have had a few drinks and that may be the issue here. But I moved married character A to the bedroom and just place character B from the top of the relationship bar with them and that's usually fine however my last two turns have resulted in cheating scandals because it's not their actual spouse.

I mean I love the drama and the assassinations but I'm not sure if it's my inebriated self making these errors full on due to my secret love of chaos, or if somehow something happened to the relationship drop down menu where their spouses are no longer at the top of the list