But, Fox News, which first reported the development, suggests that there may be ethical impropriety of some kind:
Multiple senior House sources indicated that the extent of the affair would have landed Souder before the House Ethics Committee.
The eight-term Indiana congressman is, of course, a vocal proponent of traditional family values. He has been married since 1974 and has three grown children.
"I believe that Congress must fight to uphold the traditional values that undergird the strength of our nation," he says on his official website. "The family plays a fundamental role in our society. Studies consistently demonstrate that it is best for a child to have a mother and father, and I am committed to preserving traditional marriage, the union of one man and one woman."
Souder adds: "I am committed to fighting the assault on American values."
Here's video of Souder talking abstinence education and "the failures of condom distribution" in an interview with a staffer. He also issued a report (.pdf) called "Abstinence and its Critics."
(Late Update: The interviewer in this video, Tracy Jackson, is reportedly the woman who had a relationship with Souder.)
Souder has also been a persistent critic of what he calls "homosexual marriage." He cosponsored the "the DC Defense of Marriage Act [which] would simply state that in our nation's capital, marriage means what marriage has always meant" and the "Marriage Protection Amendment [which] would amend the U.S. Constitution to ensure that marriage in the United States consists only of the union of a man and a woman."