So err. I've had Armond DeBateu in an apartment room chatting with Agent 47. Coming from 3 I felt like I could look away from SIms a little. Problem was, Armond and 47 had chemistry. Que hearing seranading from the above floor.
Now they're in love.
So yeah... Just remember no matter how happy your Sim is being single they're always one random chemistry bolt away from making out. And that's the unpredictableness I love from the Sims 2!