Emotional Affairs. That's tricky! I learned all about that in my Communication Class. If I hadn't sold back my book for money I could give you the text book explination of what one is...but alas that is not possible.
Basically when one person is disatisfied with the relationship they start seeking ways to make them satisfied elsewhere. Some turn the physical affair while others the emotional. While they seem harmless they can do a lot of damage. Especially to the spouse who is not on the other end of the emotional affair. Emotional affairs tend to give people a false sense that it's OKAY, when in reality they are not giving the attention and time to their S.O.
This causes and creates further problems in the marriage or relationship...and can ultimately lead to unfaithfulness and mistrust.
It's hard not to flirt and such when engaged in another relationship, but given the opprotunity to be in "the other person's shoes" we may feel differently.
Overall I think with the creation of the internet, there is higher risk for emotional affairs and infidelity. It's very sad
I've experienced this first hand.
I'd be laying in bed waiting for my ex to join me and he'd be on the computer (in the same room) exchanging photographs and conversations with random women on the internet. Yet, it was ALL MY FAULT for noticing.