Don't forget that adulterers don't necessarily approve of what they do. The way Jesus defined adultery (a matter of the heart and imagination), we are all adulterers...except for that dull few.
And Salvation pulls us out of that mire of conceit. And Salvation heals us from that and a million other diseases.
Ain't that a shower on the parade of the self-righteousness of the non-adulterers.
"The way Jesus defined adultery (a matter of the heart and imagination), we are all adulterers...except for that dull few."
Ahem, even the dull--remember Jimmy Carter sinning in his heart? And is he ever the dullard.
Adulterers often don't approve of what they do, but they still do it.
Also, these stats often treat a brief dalliance (sometimes caught before it gets too physical) as an 'affair.' While they can say that 1/2 of men and 1/3 of women have had affairs, I bet a good number are situations like that, or one-time events that the party is regretful of. It's probably not accurate to say that those numbers of spouses are chronic cheaters.
That's not to say it's notably less damaging to a marriage. It is to throw some water on the idea that many many people are cheating most of the time.