I knew something was up, she became distant and irritable towards me, and would get annoyed when I showed her affection, but then feel guilty and go overboard in trying to make it up to me. After things came to a head, she told me that she thought that our relationship had gone stale, and that she wanted us to open our marriage up.
I was not that keen on the idea though. As a couple in the scene we were involved in, we had played with others, but always together, never as individuals. She said she was unhappy though, so in the end, I agreed.
She came up with this idea because of the guilt she was feeling about her affair with Alex. She did not have the courage to tell me about it, but felt really bad about cheating on me behind my back. She did not want to lose what she now had with him though, so suggesting that we have an open relationship was a perfect way out for her. She relieved her guilt, did not have to own up to the cheating, and still got to see Alex! She told me she had met someone about a month later, I did not find out that she had actually been seeing him for at least 8 months until a few years later. By doing what she did, it also made it a whole lot easier for her to see more of him. Clever really!