i can see it. Yet it depends. i know a few Women who will tell you they're cheating when in fact their hubbies are fully aware and onboard.
You will never know. But when you are turned on by the thought that she's cheating, why would she even tell you the truth about their lifestyle as a couple?
Even though i don't support cheating, anyway, if a wife is indeed cheating with you on her husband, i don't see you as the one to blame. As far as i am concerned you can fuck as many wives as you (and them!) wish. In the end it's not you who breaks any vows - it's them. And they will have to live with the aftermath not you.