I agree about the one night stand. people often do things they regret, either when drunk or due to a moment of madness! But an affair is planned, it is contrived...manipulative and it goes on long enough for people to know what they are doing is wrong. A one night stand may be a breach of trust, but if afterwards you know it was a mistake then it is easier to be forgiven. But an affair is a complete breakdown of a relationship. People wouldnt feel the need to embark on an affair if they were happy in their relationship-it is selfish and malicious. Therefore, a one night stand is more forgivable.