I found this article to be well worth the read.
Emotional Affairs - Recognizing and Coping With Emotional Infidelity - Oprah.com
"Emotional cheating (with an "office husband," a chat room lover, or a newly appealing ex) steers clear of physical intimacy, but it does involve secrecy, deception, and therefore betrayal. People enmeshed in nonsexual affairs preserve their "deniability," convincing themselves they don't have to change anything. That's where they're wrong. If you think about it, it's the breach of trust, more than the sex, that's the most painful aspect of an affair and, I can tell you from my work as a psychiatrist, the most difficult to recover from.
. . .
"It's much more difficult to make your way back from a betrayal of intimate feelings than to try to refresh a marriage that may have become flat and distant. When you ignore anxiety-inducing thoughts like "I feel stuck—I wish I could run off and have fun or I feel old and dumpy—if only someone would make me feel young and sexy again," you cannot examine or deal with them in a productive manner. Instead, you unwittingly act them out, with potentially devastating results. Any good relationship takes an investment of time, effort, and emotional energy. What few people want to accept is that we can all become Sharon and Robert, and that marriage, while potentially tremendously gratifying, is always a work in progress."