I'm confused after listening to Dr. Harley define an EA as being "entirely dependent on whether or not you're in love" and reading Steve Harley's article "What is an affair?" where he says, "an affair is however the offended spouse defines it."
I don't think it is either necessary (in the sense of understanding the definition) or fruitful to compare the statements from Dr and Steve Harley. I don't think it is fruitful because using even Dr Harley's definition does not tell us how to conduct ourselves around the opposite sex. Dr Harley is not saying that it is okay to hang out with members of OS, have coffee at work, go on "platonic" dates, as long the spouse doing it does not feel in love.
If you are looking for an answer to the issue of when to send an NC letter etc, there are two articles that make it clear.
In this one,
Coping with infidelity: Beginning, a wife has a crush on her husband's friend, but the friend does not know. Dr Harley cautions against letting OM know in any way that the WW is interested in him. He says that the WW must tell her H, and together they must avoid Bob - but Bob must not be told - so obviously there must NOT be an NC letter:
So far, R.J. is not actually having an affair. She is simply drawn to Bob. He is attractive to her because he is so easy to talk to. Whenever they are together, he makes a special effort to converse with her, and he shows a genuine interest her favorite topics. The friends of good conversation prevail, and the enemies of good conversation are nowhere to be found (see the Q&A column, "What to Do When Your Conversation Becomes Boring and Unpleasant"). The pleasure of her conversation with him deposited so manylove units that she fell in love with him, and so it's natural to assume that she will want to talk to him even more. She is finding it difficult to wait for the next opportunity to see him. If she wants to talk to him more often, she will need to create new ways to spend more time with him.
R.J. is now at a crossroads. She can take the next step in developing her relationship with her husband's friend, or she can explain her problem to her husband and try to resolve the issue with him. The advice I gave her was to tell her husband about the entire situation. He should be the one she enjoys talking to the most, and her feelings for his best friend was a good wake-up call. If her husband were to learn to meet her need for conversation, the temptation to have an affair with Bob would be much easier to handle.
But if she were to do what most people instinctively do, her next step would be to tell the man how she felt about him, and ask him to get together with her more often, privately. She would tell him precisely what she wrote in her letter to me, saying that he has "rekindled feelings in me that have been dormant for a long time. I find myself thinking about you often and wish I could be with you. I feel so guilty and ashamed of these feelings, but nevertheless, they are there. I try not to think about you, but I do."
Once this honest expression of feelings is out of the bag, an affair is off and running. Even if her husband's friend had never given her a single romantic thought, the seed is planted, and starts to grow. Such an admission would lead to his thinking long and hard about his own marriage, and he would start seeing R.J. in an entirely new way. If one of his important emotional needs was not being met in his marriage, he would express his frustration to R.J., and she would willingly agree to meet that need. The rest would be history....
...At the crossroads R.J. faces, she should avoid telling Bob how she feels about him at all costs. And she should certainly not let him know that she is dissatisfied with her husband. As soon as Bob would know about her feelings for him and her marital dissatisfaction, the risk of an affair would be so great that she must end her friendship with him for life. From the moment he knows she loves him, their friendship should end.
R.J. should be able to talk to someone about her marital problems. I'm glad she had the courage to write me. We should all be able to tell someone how we feel deep inside. But R.J. should not complain about her spouse to anyone unless she has made the same complaint to her spouse. Furthermore, the person she confides in should be either a same-sex friend or a professional counselor (like me). To tell an opposite-sex friend about your terrible marriage is to invite disaster.
R.J.'s greatest failure was dishonesty. If she had been honest with her husband about her need for conversation, and they had resolved the problem, Bob's conversations with her would not have been so enchanting.
It's almost impossible to stumble into an affair if you follow the Rule of Honesty. Her husband loves her dearly, and if she were to have told him about her frustration with their conversation, he probably would have taken steps to improve. In the beginning of her relationship with him, he may have spent hours talking to her just as his best friend did. In the beginning of their relationship, she may have fallen in love with him because of their conversation. But, as so many spouses do, he began talking to her less and less, little knowing that he was draining her Love Bank.
The solution to R.J.'s problem at the time she wrote her letter is to follow the Rule of Honesty. She should write her husband the same letter she wrote me. He should know about the disaster that is about to take place so he can protect both himself and herself from it.In this one,
Escaping the Jaws of Infidelity, the wife is drawn to a man at work. Nothing has been said between them. Dr Harley tells her to move away from that job, but again there is no need for an NC letter.
So I see the question as being not so much about when he definition of an EA has been met, but about the attraction being mutually acknowledged. If it has not been acknowledged or reciprocated then it is enough to stay away from that person (and work on the marriage). However, if the feelings have been indulged and mutually acknowledged, an NC letter, and presumably exposure to the other spouse, should be done.