Once The Infidelity Starts, The Family Life Crumbles

Not only in my own experience but I have seen other situations unfold as well, that once one partner in the marriage or relationship makes the decision to cheat, normal life as it was known before that point changes drastically. They think that maybe they won't be noticed spending more time away from the family....maybe they think we won't notice that they are making changes right before our eyes, and the worst part of it all, is that sometimes we don't notice. Maybe our spouse cheated on us, not meaning to, and tell it that it just happened and they don't know why, but I believe that in some rare cases, this could be true, but most of the time, it just goes on and at that point, it's a choice that they make to do so. Family life starts to suffer because they are taking more and more time away from family things. At some point, they become more distant in the marriage as if we are not of the most importance. Once infidelity starts, family life will suffer because it's not only the "family" anymore. They have decided to bring an outsider into the mix, even if we don't know, there can be serious fall-out. How do we know if the other person they are seeing is free from disease? We also suffer because they are spending family money on that other person, so they are taking away from family money as well. Sometimes the cheater carries on for a long time and once the cheater is caught, trust is gone. Why don't they see that their actions really can devistate the whole family? Maybe they believe that they will never get caught, but most of the time, they do.