"Three is a crowd for romance..." pop up...What does it mean?

its a glitch, bc it happens to me too. now that you mention it it does always seem to happen when my sims are all asleep. ive tried Xing it out but it just pops back up, so i have to OK it to break up the group. thank you for making this thread bc i have an SP mod and just assumed it was another household i was keeping tabs on.