If she had an affair once, she will look for another one. I think she needs diversity . Either you understand and accept her as she is, or you 2 separate, the sooner the better. There's no sense in trying to make it work if this implies somehow a forced effort. I don't think a person should sacrifice his/hers happiness for the sake of a marriage. It might seem selfish, but personal happiness is more important than a marriage. At least imo. Plus - once a marriage came to have issues, the "fixing" of it looks more like an illusion or a compromise to me. Some things just can not be fixed.