Lisa and I have been happily married for over 20 years now. She is 5'2", 140, curvy blonde, DD and very pretty. Many people think she resembles Stevie Nicks of Fleetwood Mac fame. Our marriage was very conventional for many years. Had 3 kids, raise the family etc.
The very first time my wife explored sexual boundaries was after our 2nd child was born. I was away for weeks at a time, working, business trips and Lisa had to manage the household and was feeling overwhelmed, lonely and at times neglected. During one of my biz trips, a repair was needed on part of our house and I told Lisa to asked a family friend if he could help. He was a very handy guy and did a little home repair business on the side. They had known each other for many years and got along well. After the repair was complete, Lisa offered him a cold beer, they talked and drank for several hours.
As the kids slept, one thing led to another and he ended up fucking Lisa. She did not tell me about this for over 10 years - and she did not remember or would not tell me very much detail about what happened. She remembered he was very large and in good shape and she was aroused by that and said they both climaxed in the end. He wanted to see her again, for sex, but my wife felt pangs of guilt and never pursued it with him.
We have seen him socially as a couple several occassions including some family gatherings. In retrospect this was the beginning seeds of how Lisa began cuckolding me, although neither one of us realized it at the time...