I was persuaded by a man in a chat room to give him my wife's email address. He emailed her on some pretence and struck a conversation with her. He would instruct me to masturbate as we chatted before I went up to bed. Then I would cum too quick for her and she would become frustrated and more likely to meet him. Then it progressed to making me masturbate and cum so I couldn't get hard for her.
He would report back to me how the conversations were going. It took some time but they became more sexual, to the point where she told him I was failing in bed and she was frustrated just masturbating herself.
I am afraid they never did meet (that I know of), but she did start an affair some months later with someone else.