I definitely like the "before you cheat" book, but it would have to be titled and marketed very creatively.
Obviously there's a huge segment of people who think they would never cheat and therefore wouldn't pick up the book in the first place.
Maybe a title like "Something just isn't right."
Or " A short guide to fooling yourself"
Maybe " Before you regret it"
Or " What you're not telling your spouse."
Or even title it with phrases that Ws's use when they're starting to go into the fog.
"I deserve to be happy too."
"You don't make me happy, but they will."
"I would never do that to you"
"Don't you trust me?"
"We're just friends"
"No one has made me feel this way before."
"It must be love."
"I can't help myself."
It would be difficult to market to that niche who is right on the edge, because they are already starting to rationalize the thought of having a relationship outside the marriage. They may not see what they are thinking will cause all these consequences.
One thing my WS has said over and over again is that he didn't think about the consequences of what he was doing. He was high on that feeling and just felt like things would work out and take care of themselves.
Obviously a pre-Affair book would have to be strongly worded yet smooth, and also have plenty of very specific examples and personal stories of people and how they've been affected by infidelity.
It could be very interesting.