Although this couple never technically "dated," while working together on the TV show Smash, the duo was caught kissing — even though they were both married to other people at the time! After the scandal, Katherine and her then-husband filed for divorce. However, surprisingly, Michael stayed married to his wife, actress Mary McCormack.
"I don't have any regrets," Katharine later said about the affair. "All of the choices I made I learned from in a really deep way."