updated 12/28/2011 AT 5:00 PM ET
•originally published 12/28/2011 AT 5:50 PM ET
Sparks have apparently been flying on the set of the new NBC musical series Smash!
A show insider confirms to PEOPLE that Debra Messing – who announced Dec. 20 that she was separating from her husband of 10 years, Daniel Zelman – is now dating her Smash costar, Will Chase.
Chase, 41, recently separated from his wife, Broadway actress Stephanie Gibson, and the couple are getting divorced, his rep tells PEOPLE.
Chase and Messing, 43, have been an item for about six weeks, according to the on-set insider.
“It all happened very fast and it’s a difficult situation,” says the source.
Messing and Zelman have one son, 7-year-old Roman. Chase and Gibson have no children, but he has two daughters, Daisy and Gracie, from a previous marriage.
A rep for Messing could not be reached.