Samuel Pepys's diary tells of his wife walking in on him and their maid, Deb Willet.
Dr. Kate Loveman has discovered through some genealogical research at the Bodleian Library that the affair might have survived Willet's discharge and subsequent marriage.“(Elizabeth) coming up suddenly did find me imbracing the girl con my hand sub su coats,” he wrote, adding details of their embrace that cannot be repeated in a family newspaper. “I was at a wonderful loss upon it and the girl also.”
Willet married Jeremiah Wells, a theology graduate, in January 1670. Wells soon wrote to Pepys to ask if the writer could use his contacts in the Royal Navy to get him a job. Pepys obliged, securing Wells a job as a ship’s chaplain. The diarist therefore knew not only where his old flame lived, but also that her husband was away at sea. [Link]

Did you know you can read Samuel Pepys' diary online at http://www.pepysdiary.com/?
I chose to link to the complete text that includes the naughty bits, but your link is in some ways better as it turns Pepys into a blogger. Henry David Thoreau also has a blog, though not quite as titillating.
I actually have both of them in my RSS reader. The people who do Pepys' diary are really thorough, however, as they hyperlink everything almost like a wiki.
And the annotations often make for good reading as well.