From Don Juan to David Letterman, infidelity has been around as long as civilization has existed, and the Internet is still but a tiny blip in the long jaded history of adultery. But the Internet is also arguably the biggest threat to relationships that has come along since the birth of marriage, and it’s here to stay. New threats demand new rules, and the next time your partner goes online, maybe you should be worrying about if he or she is also out of line. These days, cheating and engaging in other secretive behaviors that could lead to infidelity have become easier than setting up a Wii. Technology isn’t just enabling secretive behavior, it’s accelerating it at record pace: Flirtatious friendships, emotional affairs, the return of the ex, sexting, online porn and cyber-sex—with each new advance in technology comes a new way to deceive, and more and more of us are increasingly leading “digital double-lives.” In her seminal book on emotional infidelity, "Not Just Friends," the late psychotherapist Shirley Glass implores readers to “maintain appropriate walls and windows. Keep the windows open at home. Put up privacy walls with others who could threaten your marriage.” But with the threat of the Internet, it’s not just windows and walls we need to worry about, it’s also leaks and seals. The No. 1 danger of Internet infidelity is not that it could lead to actual sexual infidelity, but that it so easily diverts precious emotional resources away from one’s primary relationship. Emotional infidelity can happen anywhere, anytime, but with the Internet and real-time digital technologies (email, texting, IMing, skyping, social networking, and others) a small leak, if left unsealed, can quickly lead to a flood. With its quick hits of newness and novelty, the Internet enables us to easily tune out and turn off to our partners, when we should be making an effort to tune in and turn on. The instant gratification of these technologies stimulates reward centers in the brain, and soon one finds oneself craving the quick hit of an instant connection or lamenting its absence. So what should you do when your gut tells you that something is wrong, but your partner refuses to acknowledge your feelings? What should you do when you’ve tried to talk, only to be told that you’re crazy or paranoid and that nothing’s going on? Well, maybe it’s time to snoop. You may not agree, but in my opinion too many people wait far too long to follow their instincts, and relationships that could have been saved had issues been nipped in the bud are instead decimated to bits and bytes. With the Internet too many people hide behind their “right to privacy,” when what they’re really trying to protect is their right to secrecy. But nobody should have that liberty. The moment you have something to hide – the moment you write an email that you don’t want your partner to see, the moment you’re uncomfortable talking on the phone in front of your partner, the moment you have to delete your Internet history before getting off your computer, the moment you have to set up a special email address for certain correspondences, the moment you’re uncomfortable sharing your passwords— that’s when the trouble begins. In a healthy relationship there should be nothing to hide. If someone is hiding something, then they should be found out. Not because they need to be penalized or humiliated, but because transparency and honesty are central to a healthy relationship. That doesn’t mean you shouldn’t respect your partner’s privacy, but respect first and foremost demands a foundation of trust. For example, I have one password for all of my various email accounts and my wife knows what it is. Does she ever use it? I doubt it, but I can’t say for sure. And she’s welcome to sift through my emails anytime she likes. But before you snoop or dig around, ask yourself a few questions: Does your spouse spend way too much time on the computer and other digital devices such as a cell phone or smart phone? Is he/she secretive about it? For example, is your spouse comfortable leaving his/her Facebook page or email open when not at the computer? Is your spouse in touch with former flames or members of the opposite sex via a social networking site such as Facebook? If so, does it make you uncomfortable? Do you feel like you don’t know what’s going on, that these “friendships” aren’t out in the open? Does your partner call you paranoid when you bring up the subject and insist on his/her right to privacy? Depending upon how you answered these questions, it might be time to snoop, especially if you’ve tried to talk about your concerns with your partner but have been met with hostility and denials. Hopefully there will be nothing to discover and you’ll be able to breathe more easily and more coolly examine why you had suspicions and where you might be able to improve your relationship. But maybe you’re not crazy. Maybe your partner is hiding something. And, in the end, knowledge is power.