Yesterday I talked with another wife emotionally involved with an old boyfriend she bumped into on Facebook. No surprise there. Every month couples enroll in our workshop for marriages in crisis because one of them - usually the wife - became emotionally and/or physically enmeshed with someone found on one of the social networking sites.

Before you lecture me about how the Internet is neither good nor bad, just a tool, please know that I am not a Neo-Luddite, technophobe, or antimodernist. It's a great thing to be able to track down old friends with the Internet. My wife Alice and I tried for years to find Rhonda M., one of my former students. We tried the alumni association, search engines, and everything else that wouldn't cost a bundle. Nothing worked until Facebook. There she was, easy to find, and we renewed our friendship. Thank you, Facebook.

However, there is another side to this. Every month I see firsthand how it can also be a bad thing to be able to track down old friends, or even to make new friends with the stroke of a key. Thousands of marriages are in trouble this very moment because someone kindled an improper relationship on the Internet. That isn't the fault of social networking sites, nor of the Internet itself, of course, but those tools make it much easier to get into these situations. We likely agree that a person that develops a relationship with someone other than his/her spouse had some type of vulnerability that preceded the illicit relationship.

Where we might not agree is how many married people have such vulnerabilities. Based on my work with couples over the last fifteen years, I'd say many people that think they aren't vulnerable are indeed vulnerable. A marriage doesn't have to be bad for one person to feel unfulfilled. It just has to fall short of what one or the other needs or expects. I wish I had kept count of the number of times I've worked with someone involved with another who said, "I don't know how this happened. I thought we were okay. How did I get into this mess?"

Recently a few people corresponded with me about social networking sites and potential marital problems.

One lady wrote, "My marriage is in trouble because of what I told myself was innocent flirting. Now I am paying the price for it. MySpace, AIM, and Facebook are all places where a married person can get into trouble. You can't go on thinking it'll never happen to me; it's ok to flirt innocently. It's not. One thing leads to another and the next thing you know you are meeting face to face, or meeting at a hotel room. Be careful and be aware of what you are doing."

Another wife wrote, "I believe the key is being aware of the dangers and not assuming ‘it can't happen to me.' Most dangerous relationships start out very innocently. The needs that are not met will suddenly be filled by someone else: Satan makes sure the void is filled."

This lady said, "Facebook and other social sites can be very dangerous to a marriage. I think, mainly, because it seems so innocent and so normal to contact people from the past, even people who are from your intimate past."

Husbands get involved via Internet connections as well, but, interestingly, most couples that come to our workshop do so because the wife became entangled with another.

How should a person make sure that s/he never crosses the line on a social networking site, or any other site?

First, always work on your marriage. Never take it for granted. Even good marriages may be corruptible because of boredom, feelings of loneliness, desire for a simpler life, cravings for romance, or just plain old curiosity. At least every six months, couples should do something together to strengthen their marriage. Work through a good marriage book, check out a marriage seminar, spend a few hours with a mentor couple, or take a long weekend without the children, work, or any interruptions and do a lot of talking about whatever comes to mind.