On Oct. 22, the former American Idol finalist was caught in a lip-lock with Michael Morris, who directed her in the now-canceled NBC musical series Smash – even though both were married to other people.
Now, a McPhee source tells PEOPLE, "Katharine is no longer seeing Michael – at least for now."
In fact, the actress' marriage to Nick Cokas, her husband since 2009, is still in a state of limbo. Despite the fact that McPhee, 29, and Cokas have been separated for months, "Katharine still has no plans to move forward with divorce at the moment, though they are not living together," adds the source.
Meanwhile Morris's wife, former In Plain Sight star Mary McCormack, prefers to keep her focus on her daughters – Lillian, 2, Rose, 6½, and Margaret, 9.
"Mary is a strong woman," a second source tells PEOPLE. "Her dedication to her children will remain her focus and gift.”
Amid all the uncertainty, one thing is true, says the McPhee source: "This is an incredibly hard time for Katharine."
Reporting by ELIZABETH LEONARD