The 40-year-old New Zealand actress, who stars alongside Chelsie Preston Crayford in the latest series of the Australian crime drama, said that she had "chemistry" with 21-year-old Pana Hema-Taylor as soon as they met each other two years ago.
Cormack told Woman's Day magazine: "There was undeniable chemistry from the start, but at the time I didn't feel it was appropriate to act on it. Pana is so charismatic. He's the sort of person who's magnetic to other people - they want to be around him. I was aware of that and then, for that to be directed at me - wow!"
Actor Hema-Taylor said that he "couldn't help but stare" at Cormack because she is so "beautiful" and knew that they had a future together, despite her reservations because of the age difference.
Cormack added: "It all fell into place. That overcame any barriers I felt might have been there."
In 2009, the couple were surprised to discover Cormack was pregnant but welcomed son Te Ahi Ka in March last year.
Cormack and Underbelly co-star Crayford recently revealed that they grew "incredibly close" during filming despite the fact that they play rival vice queens. Both stars have also explained that they "empathise" with their characters despite the "terrible" things they did.
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