4. He has an overnight change in musical taste.
"I've never really liked jazz. But I struck up with this woman, we enjoyed it together. I started listening to it all the time, just to think about her."
More from YourTango: Confessions Of Cheating Husbands
There's nothing wrong with trying new things. But when it's out of the blue and your significant other isn't exposed to the change, it's a warning sign that something is amiss.
5. He remembers things wrong or loses track of the details.
"I was talking to my wife about a movie we saw and laughing about one of the scenes. She wasn't laughing. I asked, 'What? Don't you remember?' She then informed me that we hadn't see it together."
As he spends more time with both of you, the memories of his time spent with his mistress and the memories of his time spent with you will start to blur together. Schedules get crossed and he won't be able to keep track of where he was on any given day. The time he spent with another woman will be unaccounted for — often, with no explanation.
6. He needs lots of privacy.
"I was working from home and I started closing the door more often, saying that the kids were loud or that I just needed to work quietly. I was online chatting with my mistress."
To take time for one's self is normal. But when it's out of the normal pattern—or is more and more frequent—it's a sign that something else is going in. Going into work early, leaving late, getting off the phone suddenly, taking lots of private calls from a "relative" (mom, sister, someone untrackable) are also red flags.
7. He has a drastic change in sexual appetite and style.
"I started my affair and all I wanted was sex, but not from my wife. She knew something was up, because our sex life was always pretty active."
"After I started up with [my mistress], I started sleeping with my wife much more often. She told me I was really aggressive in bed and that she hadn't seen me that way before."
More from YourTango: Fifty Shades Of Grey And You: Real Life Lessons For The Bedroom
A sudden shift in what's "regular" or familiar in bed — without a discussion of wanting something new — is a big warning sign of cheating. All of the men I interviewed expressed having the feeling of a huge rush of testosterone — which would manifest as a new confidence during sex. They felt strong, masculine, the embodiment of virility and like every woman wanted them. Their egos were growing daily. Keep reading ...