8. He hides his financial history from you.
"I was meeting [her] for lunch almost daily. And our hotel visits were three or four times per week. Covering that was very difficult. I opened a PayPal account, got a PayPal debit card and attached a personal checking account to [my PayPal account]. I would make online transfers into PayPal and she couldn't see any of my transactions."
Most cheating men will need an untraceable way to pay for things: gifts, meals, hotels, trips, etc. Refillable credit cards, PayPal accounts, eBay purchases are all great ways to try and hide large or frequent transactions. Large, random transfers or cash withdrawals should be investigated.
9. He has new "friends" at work and/or more work responsibilities.
"My company allowed me to work from home if I choose. But I had started a relationship with a new manager at the office, so I started going in to work more often. Extending my business trips a day before or after I was needed at a remote site, extended office lunches and late hours."
Office affairs are very common, especially considering how much time we spend working together. He might mention his new "friend" to dispel any suspicions you have and if you pop in to the office unexpectedly, he might even introduce you to his "coworker" to throw you off the scent. Follow your gut and pay attention to his other behaviors.
10. He's secretive with his technology.
"iMessages on the iPhone are untraceable on cell phone bills. I would only text [my mistress] when it was safe and then delete the messages immediately. To this day my wife doesn't know how I communicated with [my mistress]."
"I bought SnapChat on my cellphone to communicate with her."
"I didn't want to send email because it can be traced. So, we got a new Gmail account and communicated in the drafts folder, without sending anything."
"We bought Gliph and were sending anonymous, 'cloaked' email."
Technology has gotten smarter and affairs have gone high-tech. The signs used to be a new password on a cellphone or computer, a change in the password at your bank or cellphone company or cellphones being "left in the car." But now, cheaters can fly under the radar by using technology to do their communication dirty work. Apps exist that allow text messages, online chat sessions and pictures to last for a certain amount of time (and then disappear). Pay attention to new email accounts and new apps being used on his cell phone.
While these signs aren't foolproof signs of cheating, a few taken in combination are sure signs that something is up. My advice: don't make accusations that you can't back up. If you suspect it, sit him down for a long talk about your concerns. If that nagging feeling doesn't disappear, you have some choices to make — and perhaps some investigations to start.