Aside from the "why" question, to which I found answers that satisfied me (thanks to Barb and her website) there's a practical part of this fetish as well. I assume, that like a lot of men my only gripe about our (my wife and my) sex life was the frequency. Just not enough times during the week to keep the Bear happy. That's as much a compliment to my wife as it is a confession of my sex drive. I decided that "straying" was just an all-around bad idea for lots of reasons, so I made the conscious decision that I would make the women in my fvf videos the "other woman" in my marriage. That way nobody gets used, feelings hurt, etc. So, to all of those women, I'd lke to say "thank you."
Granted, pretend sex with a screen image doesn't come close to the real deal, but it's kept me out of trouble.