So far I can confirm her letters to her mother are every bit as entertaining as her mainline literary work. It is absolutely crazy to me that she had this opportunity in 1922!

"But Poirot, you can't deny the romance and mystery involved"!

"Mais oui, but there is no mystery"!

"What? Do you mean she did not disappear?"

Poirot sighed; "Ah, no, she did disappear but there is no unsolvable mystery to it."

"How do you account for it then?"

"Précisément, by taking her word for it! How you say? "she cleared the air" in an interview to the Daily Mail published on 16th Feb 1928" - https://agathachristie.fandom.com/wiki/Her_Own_Story_of_Her_...

"But she might be making up the whole thing!"

"Maybe Mon ami, but there are enough facts to tilt the balance of probability against it."

"Like what?"

"Like her mother's death, fight with her husband regarding an impending divorce, wrote letters to her two brothers-in-law and not to her sisters or other women, drove to and talked to her mother-in-law, registered in a hotel under the last name of her husband's paramour, thought of suicide, went to Harrogate etc. Now what does that tell you?"

"I don't know".

"Mon enfant (i thought this was rather uncalled for), How many times have i told you to employ the Les petites cellules grises regarding The Psychology?

"Thirty-six thousand times?", i answered slyly.

Poirot gave me a severe look, but continued; "She met her mother-in-law and wrote to multiple brother-in-laws. What could it be other than asking them to intercede on her behalf with her husband?"

"But why did she go to Harrogate and register under a different name?"

"Not under any name but under her husband's paramour's last name. That tells you that she probably was a) maybe trying to have The Fling as a means of getting back at her husband, OR b) as a psychological means of coping about getting back with her husband under his paramour's name".

"And the attempted suicide?"

"Probably depression brought on by accumulation of all of the above all at the same time (plus the pressure to come up with the next bestseller); but maybe second thoughts about her Mon enfant stopped her."

"Poirot, i do believe you have solved it!"

"Mais oui, Mon ami, I am Hercule Poirot!"

PS: Couldn't help myself since i am currently reading the collection; The Complete Short Stories Hercule Poirot Over 50 Stories.