So, I married my Simself to Param Singh of Moonlight Falls and she was pregnant with his child at the time. I then proceeded to move in Argus Brown, who then rolled the wish to kiss her for the first time (not sure whether that was down to his Inappropriate trait or not) and I let him kiss her, then Argus asked her to break up with Param and bam! He was now her ex-husband immediately. I knew the "Ask to Break up" option was quick, but not that fast!
Now Argus is enemies with Param and my Sim has 3 kids with 2 men!!!