Man, Nietzsche would have loved this story! (Perhaps he actually did, he loved Maupassant after all.) It seems to be about the ascetic, the victim of nihilism. Someone who unfortunately has been made so ascetic and anti-life such that they are so sensitive to everything, to even the smallest pain or touch (cf. The Antichrist, or perhaps Twilight of the Idols) such that they have grown to hate suffering which appears to be a ubiquitous or even necessary element of life and Reality and therefore such sad pathetic (though not blameworthy, since he's a victim of such experiences and thoughts and also since he couldn't have done otherwise!) souls grow to hate life and Reality as a whole, limiting their experience to only a narrow sliver of the wide range of human experience and emotion. Many other Nietzschean elements too. The lack of desire and ambition prevalent in nihilists and others who have a corrupted or decadent or degraded "will to power", excess pity (that perpetrator of unnecessary suffering), altruism to the detriment of oneself, thinking one isn't "made for this world" (which suggests a preference for the otherworldly over the thiswordly, as is corroborated by his being a priest). What then would I have done were I in his shoes, his circumstances? After all, traumatic experiences and being perpetually anxious are not entirely foreign to me and also could well one day happen to me. So think! Hmm. Well, go to therapy, for one. Choose an attitude of acceptance towards life, Reality as it is and Reality as a whole, including my own anxiety and other emotions, and including my own bodily and physiological state (including the symptoms or physical realisation of my anxiety). But certainly always to choose acceptance, amor fati and love of God or Nature: love of Reality. Nothing shall ever come between that. It is always an available option no matter what, come what may. And to nurture and grow my desire and striving for flourishing, both MY OWN and that of others, which stems both from my nature and also from the love of Reality (love entails a striving for flourishing after all; and where is flourishing happening in Reality?—living things, so far as we know. And humans, pre-eminently, as far as we know. And one particular human, as far as it seems right now, which is the most within my power to determining the flourishing of: myself.) Of course, many people's inability to do all this cognitive, conative and acceptance work is itself a fragment of Reality, and therefore ought to be accepted to, by the flourishing, capable person.
Anyway yeah. Perhaps try to reread the story again without my Nietzschean/Spinozistic lens. Also Maupassant is a lovely and interesting writer! Should read more of him. Loved his Necklace too.
Anyway, I read this book as part of 50 Great Short Stories (ed. Milton Crane).