I think emotional affaires are a big spectrum, unlike physical affairs.
The minute people kiss/ fondle/ never mind have sex they KNOW they are breaking the rules and betraying.
But emotional affaires are really unclear. On one end of the spectrum, it's an innocent friendship with perhaps a little underlying chemistry, which is managed respectfully and responsibly. On the other end of the extreme, there is lying, covering up, dissing the partners, fantasizing, and preparing to escalate to the physical.
I think on the first end of the spectrum, right and wrong is not very clear.
I had a very close male friend for about ten years while I was married. He was 25 years older than me and lived in a foreign country. Neither of us ever revealed with a gesture, glance, word never mind action, anything we felt for each other beyond friendship (and even now I don't know what he felt for me!). We always spoke about our spouses with total respect, never complaining about our relationships. Both spouses knew we were friends and the four of us met together sometimes, and there was nothing said in our correspondence that either spouse could ever object to.
But there WAS an energy and attraction of some kind that was different to friendship. I just felt it. And I looked forward to seeing him and receiving his emails in a way that I didn't with anyone else. In a parallel universe, I can imagine we might have dated - though I am also quite sure it would have ended in disaster! It is possible on some level it created a pocket of emotion/energy in me that distracted me from my spouse.....I was conscious of 'limiting it' - for example only writing one, lengthy email per month to make sure this didn't take over too much.
Was I having an emotional affair? Perhaps.... I still don't really know.