For marriages that are struggling, it's surprising to many people that having an affair can help to
save it. Sometimes the 'right kind' of affair can be a positive thing, resulting in folks not taking things for granted. The problem is society as a whole in its conservatism, has stigmatized infidelity, thereby preventing the discussion of the positive advantages to having an affair.
It's not saying that one should be open about having an affair within a relationship, on the contrary, most cheating partners should keep quiet about it because the main rule of thumb is that revealing you are having an affair will always be more damaging versus being discreet about your infidelity.
For the party who has decided to have an affair, it may be the final push to change as a reaction to a relationship that is not working. Most folks who do have an affair are good people who are just trying to find true love and happiness, as compared to those losers who just cheat for the sake of cheating.
For these good people, that have looked into how to have an affair or are already there, the infidelity can even be therapeutic, giving their relationships a sense of clarity and the impetus to change things, the equivalent of shocking the system. All through this process, the party who is having an affair should never admit to it even if asked directly by their spouse. Admission to having a lover or mistress will always cause more damage in the long run, so this is one case where honesty is not really the best policy.
Most of the time, women cheat when their emotional or sexual needs are not being met. Men, on the other hand, due to biology, can be 100% happy and fulfilled in their relationships and still cheat.
Relationships are unique in terms of problems and how people make them work. For some, the attitude is if it does not work, have an affair or just move on. For others, having children come into play on how to handle having affairs. For example, there are those who have been together for years, where sexual activity and libido has gone down, the wife refuses to have sex anymore and the husband still has the need.
In this case, while there are those who say the husband can just leave, the more practical solution would be for the husband to figure out how to have an affair to meet his needs, while at the same time keeping it discreet and keeping the family intact.