New York, Jan 8 : Experts say that having emotional feelings for someone is the start of an affair, but actor Brad Pitt, who was married to actress Jennifer Aniston when he shot `Mr. & Mrs. Smith' with actress Angelina Jolie, has denied that he cheated on her.

Pitt, 45, has once again rebuffed allegations that he started his affair with Jolie on the set of `Mr. & Mrs. Smith' while he was still married to Aniston, and says that he was still filming the movie when he split up with her.

"What people don''t understand is that we filmed for a year. We were still filming after Jen and I split up," the New York Daily News quoted him as saying in the February issue of W magazine.

"Even then it doesn''t mean that there was some kind of dastardly affair. There wasn''t," he added.

But experts have pointed out that an affair is not just about sex, but also about emotions.

"An emotional affair is an affair. If you find yourself having feelings for someone, that is the beginning of an affair," Rachel Sussman, a New York-based marriage and family therapist, said.

So whether Pitt and Jolie consummated their relationship while he was still married to Aniston is irrelevant, she says.

Both Jolie and Pitt have denied that they began dating during his marriage and Pitt now says that his early relationship with Jolie was "respectful" of his marriage with Aniston.

But Pitt''s definition of what''s "respectful" might differ from his ex-wife''s.

"Men do tend to walk around feeling that unless I''m having sex, I''m not doing anything wrong," M. Gary Neuman, psychotherapist and author of "The Truth About Cheating: Why Men Stray and What You Can Do to Prevent It," said.

"Women can be uncomfortable with the husband talking about how many lunches he''s had with an associate. There is a difference of perspective," he said.

Adding that extramarital sex "is only painful because it says how far the emotional affair went."

Both Sussman and Neuman agree that spouses can avoid becoming too close to a member of the opposite sex. (ANI)