Common Knowledge Isn't Common Anymore

Another "Last Resort" candidate for my Sinclair Dating Service.

I, along with about 30 others, was fortunate enough to overhear a breakup happening in Building 5 today.

I'll skip the boring parts and dive directly into the juicy bit.

Guy: "Why did you cheat on me?"
Girl: "If I knew sleeping with him would piss you off, I wouldn't have done it."