When does close friendship turn into emotional infidelity?

If you’re having a hard time in your marriage, is it wrong to talk to someone else about it, or to share intimate secrets with a friend?A few weeks ago, I wrote a column about infidelity in which I referred to “emotional infidelity” – what used to be called “an affair of the heart”. Just what does it mean to be emotionally unfaithful in a time when email, instant messaging and mobile phones give us more private ways to connect than ever before?