Thanks. The couple that got divorced still has a relationship value of +100, so there's no disliking involved. There wasn't any drama, either, they had just been living apart for some time. I'll change Romance to Disallow, which was the recommended setting, anyway. I wouldn't mind the occasional fling, but I don't want them to divorce out of the blue.
OK, I guess that "Faithful" moodlet has some issues. With my founder, one of the problems was a "romantic interest" that kissed him once close to the start of the game and then moved out of town. She still counts as his "longest going relationship", even though she doesn't exist in the game anymore. I'm more surprised by these eternal moodlets. But yeah, Jamie started her outside relationships at home, which seems to be a safe place. Woohooing with your date at home in front of wife and kids also seems to be the safest way to not stir any suspicions.