Trying to find novel about a woman who goes into deep introspection while stranded away from home

Question

The woman is upper-class British, stranded I believe somewhere in the Middle East late 19th century or so (she's waiting for an often-cancelled train). While stuck there alone, she starts to realize that her husband was madly in love with a friend of theirs; her children have rejected her, and so on. At the end, as she finally travels back into more hospitable Europe, she decides she was fantasizing and none of that could be true.

I read this 25 years ago, but my impression was that it was written by a British author during or shortly after the time-period in the book.

Answer 1

I believe this is 'Absent in the Spring' (1944) by Agatha Christie (writing under the name Mary Westmacott).

The book is later than the questioner thought, printed in 1944, but very much in the period of the Empire. Otherwise their memory seems to me exact. Wikipedia has a good article:

"Stranded between trains, Joan Scudamore finds herself reflecting upon her life, her family, and finally coming to grips with the uncomfortable truths about her life."

J. D. Beresford's review in The Guardian of 25 August 1944 concluded, "It is a very clever and consistently interesting study of a character that not even a desert vision could permanently change."