My Mortal Enemy by Willa Cather

The first of my lesser-known-to-me Willa Cather purchases whilst in Oxford and  My Mortal Enemy is more of a novella set in what I would normally envisage as Whartonville not Catherland. This is New York society, as fifteen-year old Nellie Birdseye is invited to travel from Parthia, Illinois along with her Aunt Lydia to spend Christmas with Myra Henshawe in her Madison Square Garden, brownstone apartment.
The high-spirited Myra had grown up in Parthia, adopted as an orphan by a wealthy local businessman,eventually risking his wrath and subsequent disinheritance from the family fortunes by eloping with Oswald. It's been the talk of the town ever since and initially what's not to like about someone who gives up fortune for true love.
'All Myra's friends were drawn into the web of her romance' and Aunt Lydia clearly remembers every last detail of that 'thrilling night' of Myra's winter elopement, me too.. the first hint of snow and sleighs and I'm there and thinking of more Edith Wharton and the inimitable Ethan Frome. Young and impressionable, Nellie is transfixed by the confident and charismatic Myra, the hostess with the mostest, but also mystified when asking Aunt Lydia of Myra and Oswald's life...

'But they've been happy, anyhow?' I sometimes asked her.
'Happy? Oh, yes! As happy as most people.'
That answer was disheartening; the very point of their story was that they should be much happier than other people,'

With their increasing acquaintance little snippets and snitches of dislike creep in as Nellie starts to see Myra in her true colours, the falsities and the duplicitous behaviour, the moneyed friends who would certainly not be friends without the money, the unforgiving nature of Myra's temperament and slowly the illusions are replaced with the reality

'When kindness has left people, even for a few moments, we become afraid of them, as if their reason has left them. When it has left a place where we have always found it, it is like a shipwreck; we drop from security into something malevolent and bottomless.'

When Nellie stumbles across Oswald and Myra living in very different circumstances some years later, there are more lessons to be learned by everyone before Willa Cather has finished her story. 
My Mortal Enemy is short, readable in one sitting but I took plenty away from that one sitting.
Marcus Klein in his 1961 introduction to my US Vintage Classics edition suggests that the book may have been based on a personal experience in Willa Cather's life. The mortal enemies are several and various, different for each character and I spent a while defining them once I had turned the final page and allowed the mood of the book to swirl around in my mind.
Marcus Klein argues that

'Willa Cather's mode was elegy, and as it must be for all elegists, the enemy was time, mortality itself.'

Klein also examines a 1936 essay by Willa Cather on the fiction of Katherine Mansfield,

'human relationships are the tragic necessity of human life; that they can never wholly be satisfactory, that every ego is half the time greedily seeking them, and half the time pulling away from them..'

but on reflection never has such a conflict been more evident than in the books I have read by Willa Cather to date, My Antonia, The Professor's House and now My Mortal Enemy.
Even more interesting to me for an ending that bore great similarities to that of another recent read which played tricks with my sense of disbelief, The Night Following by Morag Joss (more of that soon) yet why was my disbelief not stretched beyond capacity here?
Just how did Willa Cather sneak it through as believable, appropriate and entirely in keeping with the book?

My admiration for Willa Cather is growing steadily, book by book and it was back to A Jury of Her Peers and Elaine Showalter for more thoughts.
Elaine Showalter cites Sarah Orne Jewett as Willa Cather's great literary mentor, reminding me that I have had The Country of the Pointed Firs at the ready for about the last ten years, but I was intrigued to read of the letter that Sarah wrote to Willa, 'passing on the professional torch to her' and urging her to forsake journalism for a full-time writing career,

'If you don't keep and guard and mature your force, and above all, have time and quiet to perfect your work, you will be writing things not much better in your life than you did five years ago...you need to dream your dreams...to work in silence and with all one's heart, that is the writer's lot; he is the only artist who must be solitary and yet needs the widest outlook on the world.'