Nobody does Edgy Catholic better then Graham Greene! We give The End Of The Affair an Edgy Rating and a Totally Catholic Rating.
The Edgy rating derives from dealing with the subject of adultery, and the unusually stalky move of hiring a private detective to follow around your ex once she's left you.
The Totally Catholic rating comes from this work fitting into so many Edgy Catholic categories at the same time. There is a redemption story, a conversion story, a saint-like story, and a faith failure story in this one. Graham Greene pretty much captures everything we mean when we talk Edgy Catholic in this work. But in 1951, when The End Of The Affair was written, mature themes from a Catholic perspective were more common in literature, and so there was less need to define a category for works like this one.
By the way, the remake of the movie based on this novel from 1999 is a classic example of taking a wonderful Edgy Catholic work and subjecting it to a Hollywood style Catholic-ectomy. If you take the Catholic perspective out of this work, you have nothing left but Graham Greene's name on a dung heap. I have not watched the original movie from 1955, but the 1999 remake is just awful.
You can check out this Edgy Catholic favorite at these links: