A few years ago, a handsome young colleague of my wife noticed the effect his good looks had on her, and set himself the challenge of seducing her.
Kudos to him, the lad was aptly skilled in this area and took his time to charm her one small step at a time, so over time my wife progressively fell for his ongoing little spiel.

At home she was open and honest about it, and one day confessed her turmoil and confusion to me. Indeed, whilst she openly amitted longing for an intimate relationship with this young man, she also declared valuing our own intimacy and the security and stability of our marriage, and not wanting to lose any of it.

In the times that followed, she and I discussed the situation continuously, as the young lad intensified his efforts to win her over. Judging by her responses he was clearly on a winning path, and this was not a battle a jealous husband was ever going to win. I settled for managing the impact and eventually we struck up a deal:

• At home, with our parents and at family events nothing would change, our marriage would be unaffected and in our own time we would continue sharing the same level of intimacy as before in the secrecy of the marital bed, but most likely at a reduced frequency. In time, if and when her relationship on the side finished, we would resume our marriage as if nothing had ever happened.
  
  
• In exchange for the above I had to agree to several things:
  
  
• For the rest of society (friends, acquaintances, colleagues...) we would be "on a break" of indefinite duration. My wife would permanently remove her rings and behave as a "free woman". As such she would be legitimately entitled to being with a new partner, to being seen with him in public, and to attending social events with him. She expected me to play the game and support this story in any and all circumstances.
  
  
• Those same privileges would not apply to me however. Indeed my wife could not bear the thought of me being with another woman. She strictly forbade me to even contemplate the possiblity and made me solemnly swear on our children's heads that I wouldn't.
  
  
• For as long as it took I would have to be acceptant of her extra-marital relationship and even be supportive of it, both in practical terms and financially. This would involve looking after the kids in her absence, paying for taxis, meals and even hotel nights, buying her nice clothes and helping her choose sexy lingerie even, giving her lifts when able to, giving her advice on what men like (including sexually), make honourable excuses for her absences when required, etc.
  
  
• And of course I had to agree to her total, unlimited and unconditional sexual freedom, including the principle that if something happened (e.g. pregnancy) that I would be fully supportive and agree with her that we would do 'the right thing' (knowing full well that she would never go for a termination). 

I agreed to all, and the next time the young lad made a move on my wife she gave in. Their first date was set for the Friday night of that week. She started preparing herself long in advance to make herself look stunning for him, and that day she also took her rings off as she said she would. He picked her up at our house at 8pm and dropped her back off just before midnight. I waited for her and when she entered the house she admitted that they had spent long moments in his car parked just outside our house, kissing and... 'touching'. 

 For their second date the week after, the lad leveraged a friend at a nice hotel, and was able to book the nuptial suite for the price of a standard room. When they arrived, the entire staff referred to my wife as "Mrs" and the lad's last name! So that night my wife also became his wife, and the little bastard made sure to give her a honeymoon she would never forget, thus making his permanent mark on my wife.

And so began our menage-a-trois and my wife was ecstatic, with two men regularly making love to her: one with the passion and energy of youth and the other with the comforting warmth of a stable marriage. Whilst the young lad's sexual performance was clearly superior, mine improved too under competitive pressure, and so my wife's sexual activity tripled in frequency and intensity! 

In an effort to secure the young lad's affections long-term, and to counter competition from younger women, my wife indulged all of his sexual requests, no matter how vile or degrading they might be. The lad got her to downgrade her hair, makeup and clothes to adopt a more vulgar and provocative style, he shaved her pubic hair himself and he soon began to demand of her acts typically seen in hardcore porn movies including group sex, sodomy, facial ejaculations and more. Over time his kinks grew in perversion and he perverted my wife into public or online exhibitionism, where my wife would be expected to strip, show herself off and even dance naked, then perform sexual acts on him, sometimes in front of hundreds of strangers online. Other practices included mild prostitution (selling her body to his mates), mild torture and watersports even, often in public.

For the horny young Casanova  my wife was just one of three dirty married whores he was having his fun with on the side. After almost an entire year of soiling her with degrading sexual treatments he eventually declared her "second-hand" or "damaged goods", and decided to replace her with "fresh meat". At the end of a brutal final sex session with my wife the lad dumped her unceremoniously and sent her back to me broken and humiliated. Before dismissing her however, the lad reminded my wife how much blackmailing material he had on her, to ensure she would never seek some sort of revenge on him.