First off shall say I have never liked Robert Graves much - very pretentious, arty, cliquey set,, upper class, monied, swanning off worshipping the muse in the Med in arty communities, Yawn. I have read of some of GOODBYE TO ALL THAT too and many war poets.
This film is very slow, overlong too, very wordy and a very female film - the writer/director has written/directed nothing else, so must have great contacts.
I just did not care about the characters and some were beyond annoying I wish they'd go back to the front (the women esp, the American one). Watch to the end to see what they did after WWI. Not a lot really, as they were upper class rich so just played.
Watch 1917 instead or ALL QUIET ON THE WESTERN FRONT (1930 version is the best of 3), or The Burying Party (2018) on Wilfred Owen, or the great Benediction (2021) all about Shellshock (or watch Ian McKellen and Brendan Fraser in the class Gods and Monsters.
This? 2 stars max.