Katharine McPhee has been married to Nick Cokas since 2008, and she just pulled a Kristen Stewart when she was caught sucking faces with the director of her former show Smash, Michael Morris. He himself is married to actress Mary McCormack. From TMZ:
Sources close to Katharine and Nick tell TMZ ... the two have been separated for 6 months and are living apart. They were married in 2008. It's unclear where Michael's relationship with Mary stands -- but it seems it's also on the ropes, because over the weekend he was sucking face with Katharine in broad daylight in L.A. like he didn't care who saw.  The two weren't shy with the PDA either -- holding hands and cuddling each other in Hollywood.