What the Founders failed in was in assuming that the same morals and values and society would still exist without having to write it down on paper.
And Mark Sanford's reign as governor of South Carolina is something that the Founders would certainly not have said was merely “okay” because they did not specifically address fornication and adultury in the Constituion.
Your post is interesting.
The Constitution does not address fornication and adultery. That is in the Bible.
If the good people of South Carolina decide to forgive Sanford, that is their choice. Not the federal governments.
The founding fathers were not “chaste”.
When you get some time, you may want to read the Constitution.
Have a good evening.