This is why we need this advice:
A campus minister once told me of a concept called, “emotional chastity”, or the idea that there’s really no reason to share certain kinds of information with people you don’t know well or have a tenuous relationship with. I’ve been at parties where a guest whom I barely know will start telling me intimate details about her personal life. This information is inappropriate without a larger context with which to understand her. In other words, certain kinds of relationships come with understandings and privileges that others don’t.
I also think that valuing this spousal privilege is important to upholding the dignity of marriage in the public square. Marriage needs to be set apart and elevated as an institution that fundamentally structures our society. It sends the message that there are privileges that come with pledging one’s life to another and sticking with it for life. It makes marriage the kind of relationship that society recognizes as elevated and respected. If we don’t treat marriage with a special sort of reverence in our own lives, why should the opponents of marriage?
Now, obviously, if there are problems obviously they should be discussed in an appropriate forum and it is of my personal opinion that the occasional discrete conversation with a trusted girlfriend is fine. If we want to promote the importance of marriage, however, I think we should all make an effort to uphold the dignities of our own individual marriages by giving our spouses a trusted environment to love.