I’ve always had this, and thought it was just a weakness in the basic design of the game rather than a bug per say. Because moodlets aren’t really targeted at anyone, they’re just general. So if a Sim becomes flirty because of flirting with their spouse - or, after the sentiments update, simply because of being near their spouse who they have a romantic sentiment with - they now are generically flirty and will flirt with everyone. Just like if they get an angry moodlet because someone insulted them, they’ll knock over their own trash can and insult their kids, while a happy/confident moodlet will see them act friendly even with the spouse that just cheated on them and the random stranger that just insulted them.
