Debra Messing, who announced her separation from her husband, writer/producer actor Daniel Zelman (pictured at left with Messing), on December 20th, is dating her Smash co-star, Will Chase. Smash is NBC’s new musical series starring American Idol runner-up Katharine McPhee, which debuts February 6, 2012. Chase, 41, also separated earlier this month from his spouse, actress Stephanie Gibson, who is his second wife. A show insider told people.com that Chase and Messing, 43, have been an item for about six weeks, saying, “It all happened very fast and it’s a difficult situation.” Messing has a seven-year-old son, Roman, from her 11-year marriage to Daniel. Chase has no children from his two-year marriage to Gibson, but has two daughters with his first wife, Lori.