The problem I am having with this emotional affair thing is that is so subjective.
I give time to all of my friends emotionally. And sharing secrets, hopes and desires, to differing extents, is a part of any meaningful friendship. I do this with my male friends as well as my female friends.
The key part of your description is the "not meeting the emotional needs of their current partner". Of course you can fail to meet the emotional needs of your partner even if you don't have any friends.
And, of course, there is the question of which of your partner's emotional needs are you responsible for meeting? If are dependent on one person (your partner) for all of your emotional needs, I think this unhealthy. The best relationships, in my opinion, are where both partners have close friendships outside of the relationship.
A Physical Affair is so cut and dry. If you are my girlfriend and you have sex with someone else, you are cheating. If you kiss someone else, you are cheating. There is a clear line. Obviously there is some grey area, if my girlfriend flirts excessively I might get upset. But, there is a clear line to a Physical affair.
But if my girlfriend has a friend (who isn't me) that they aren't sleeping with or kissing, do I have the right to be jealous? Does my feeling that isn't meeting MY emotional needs give me the right to demand that she not give continue in her relationship with her friends?
If I accuse my girlfriend of having an "emotional affair", this gives me the right to control who she is friends with and how she relates to her friends. I am not comfortable with this, particularly when the definition of "emotional affair" is so unclear.