"The script" just means that most affairs follow one of just a couple of basic scripts. Every wayward thinks THEIR relationship is "special," but the truth is they all are pretty much the same, and you can predict much of what is going to happen.
An example would be, if you decide to expose the affair, the cheating spouse will say "Well NOW you've blown ANY chance you had! I was GOING to give you a chance, but now you've BLOWN it!"
Another example would be the "re-writing of marital history," where the cheating spouse says they were NEVER happy in the marriage, never in love with you, even though you have years and years of great memories together, and scores of Valentine's and anniversary cards with notes that say just the opposite.
