The recent Time magazine article made the point that Infidelity is on the rise, but that it is not due to the fall of morals or the reduced status or religion or any of that - it is due to opportunity.
A couple living in a small town where they met knew only a relatively small circle of people and had only one car, etc simply did not have that much opportunity to have affairs.
I think the biggest impact of all is the recent rise in cell phones, email, facebook, etc which put anyone immediately in private, intimate contact with anyone anywhere.
Just think of EA's. 20 years ago, to have an EA a person would have arrange clandestine meetings at coffee shops or make hushed phone calls from a locked bedroom or closed office door. Now...
I am now sensitive to it now and notice it wherever I go. I was at the beach last week at a family resort area. It was the middle of the week, so there were mostly women with kids on beach (fathers were at work??) At any given time I could look around and see 1 in 3 of the women on her cell phone. To whom??
Yes it is on the rise, globalization, the internet, cell phones and any other new fan dangled way of communicating to other people contribute to this.
The potential may have always been there in the past, but the means to realize that potential to cheat & have affairs is what has activated the increase in infidelity.
Incidentally, after a while when I finally really got sick & tired of the talking & texting to other people by my W (which included other men), I called the wireless provider and suspended the phone. The cellphones we have are both under my name (the account is in my name) and I had realized that I was enabling her to do these things and financing them at the same time, I felt so stupid that it took me that long to realize this. When I did end up suspending her phone so that it no longer worked she did get extremely mad at me ("how dare you?! why are you trying to control me?! etc.), I just replied in a calm fashion that me paying for a cell phone for her to use to speak & text other men was her controlling me, not the other way around. I told her she is free to get a cellphone of her own, buy one, lock in a plan and pay for it herself - that way I don't have to pay for a phone that isn't going to be used to call & text me.
We may not be able to stop our spouses from calling & texting potential affair partners because they can do whatever they want to do and it's in your best interests to promote their free will just remember to respect yourself enough to set a boundary that says "I'm not going to pay for you to be able to do this, you can pay for that yourself".