You've met someone online. What do you really know about them? Or, what if you've met them offline? Increasingly people are "cybersleuthing" for answers, using the power of the Internet to give them insights into the people they've met. Here are three of the most common situations:

Dear Double-Checker, Don't call the whole thing off just yet. It's entirely possible this is an honest mistake. Remember, there's a big difference between an active profile and active dating. He's been with you for four months now and may have completely forgotten about his online membership. That's a good thing -- it means he's into you instead.

Having said that, I know you'll get much more peace of mind when you see hard evidence that his membership is on hold. The best approach is to make a joke of the situation. Say something like, "You know, the other day I took a pretty big relationship step and switched my online profile from active to inactive. I couldn't help but notice an eligible bachelor who still looked a bit too eligible on the site."

If he's a good guy and this relationship has a future, you'll see his membership go on hold quicker than you'd reach for a glass of water after a spicy meatball. If you hear excuses, he gets defensive, or refuses to change his membership status, it's time to get concerned.

Dear Friend, There are two schools of thought on this one. The first says to mind your own business. Even though you have hard evidence of a cheater, it's not your place to play judge and jury on other relationships. The second theory says you have no choice but to tell what you know: share the information with your colleague and let her do what she wants with the information.

So what's the right answer? It really depends on the nature of your relationship with the colleague and how you feel about getting involved in other people's business. While you may believe you have clear evidence of a cheater, your colleague may not see it that way. Once you share this information it may change your relationship with the colleague forever. A changed relationship could have a big impact on your daily happiness at work.

You may think you can share the evidence and disappear again. But it may not go that smoothly. You'll obviously have an upset colleague on your hands, as well as a guy who is upset about the accusations. So just understand that getting involved in another relationship means just that: you're involved, and the consequences may be beyond your control. On the flip side, if you know this relationship has serious marriage potential, maybe it's worth the risks.

Dear Snooper, The minute you bring up these suspicious emails, your partner will completely turn the tables on you. You'll hear things like, " How dare you look through my personal stuff!" or "Since when don't you trust me?" or "Who said I have to tell you about every little detail of my life?"

Beware, these are defensive tactics aimed at diverting attention from the matter at hand. First off, you do need to apologize for snooping. The fact that you found something doesn't make it OK to rifle through your partner's stuff. So be apologetic and take accountability.

Once you get past the table turning, it's time to deal with this mystery stranger. The key is to watch your partner's body language and listen closely to his explanation. The saying goes "People with nothing to hide, hide nothing." So if you really have nothing to worry about, your partner should immediately come clean about this person, the nature of their relationship, and why you never heard about this person before. If your partner comes clean right away, then let this go. If your partner is evasive, defensive, and refuses to come clean, then you just might have a cheater on your hands.