I agree that people should try their best to keep the marriage together. There is a lot to be gained by keeping two people together in a loving marriage. I know of one guy whose wife had an affair, and he ended up adopting the child of that affair when they reconciled. Now that is fellow who takes his marriage seriously.
One thing many people have not mentioned is that all to often these days, there is a 3rd Party who is working hard to pry the marriage apart. The 3rd Party often provides a very safe and emotionally comfortable environment for one of the married persons. Time with the 3rd party is usually free of child rearing issues, money issues, and the often mundane issues of day to day life as part of a family. Time with the 3rd party is usually exciting, new, different, and often it is in a vacation like environment. What fun! What a relief! What adventure! What a disaster for the marriage and the family unit.