Love's Civil War, Edited by Victoria Glendinning with Judith Robertson

Love's Civil War is a most peculiar record of a long-distance love affair. Elizabeth Bowen met Charles Ritchie at a christening party in 1941. She was 41, a leading light of the Anglo-Irish ascendancy and the celebrated author of The House in Paris and The Death of the Heart. Charming, loquacious, impulsive and confiding, with a gift for witty description and warm friendship, she was a dazzling presence in the literary salons of wartime London.

She had been married for 18 years to a kindly but sexually inert administrator called Alan Cameron. Ritchie was seven years her junior at 35, a Canadian diplomat on the make (later to become ambassador to the US) who, despite his melancholy, Larkin-ish face, was a charming ladykiller, attracted to "rococo Romanian princesses and baroque dilettantes." A spark was kindled at the christening and writer and diplomat embarked on an intense affair, whose ramifications rocked their lives for 32 years until her death in 1973; he brought her champagne at the hospital, and was with her at the end.

From wartime austerity, through a widowhood and a marriage, right up to the Swinging Sixties and beyond, Bowen and Ritchie wrote to each other across huge distances and gaps of time. Charles was posted to Paris, Ottawa, Bonn and New York; Elizabeth tacked busily between her marital home in Regent's Park and her Irish family seat of Bowen's Court, Co Cork. Their stolen days and nights together were few, hungrily anticipated for months and rapturously reviewed (as it were) for months afterwards.

Bowen's letters display, perhaps more than her delicately nuanced, Jamesian novels, her exuberant enjoyment of life. They're full of vivid evocations: visits to America, Rome, Madrid ("a much more flary-glary city than I'd imagined... modern and rather South American-looking. Great parts of it feel rather like the Tottenham Court Road") dinners and meetings with literary friends (Cyril Connolly, David Cecil, Nancy Mitford, Virginia Woolf, Isaiah Berlin), books read, clothes bought, food consumed, gifts of make-up ("I had certainly never even heard of the 'fluffy' vanishing cream. I can't tell you what heaven it is to put it on the face"), memories of Charles's conversation, his physical beauty ("the most adorable glowing face") and her confidence in the uniqueness of their love ("it has an independent existence of its own, outside temporary anguish and loneliness").

The flow of brittle charm seldom subsides, but there's an urgency about her protestations of love. You get the impression she kept the affair going by an act of determined will. This feeling is reinforced by the one-sidedness of the correspondence. Ritchie destroyed his letters to Elizabeth after her death. We have no record of his intimacies, insights, promises or undertakings; none of the thousands of ways he beguiled her over 30 years. As a kind of booby prize, we're given extracts from his diaries which, compared to Elizabeth's life-enhancing missives, are thin fare: self-denouncing and cheerless bulletins from a bored sophisticate who was wildly successful with women but didn't like them much.

Early in his affair with Elizabeth, he wrote: "It's a waste of time trying to discuss character, personal behaviour etc with a woman who is in love with one: it always comes back to a few simple variations on the one theme." As he contemplates lonely middle age and the need to settle down (he married a cousin, the unfortunately named Sylvia Smellie, in 1948), it becomes painful to read Bowen's cries of self-reassurance that their love will survive.

One reads, between the lines, the aching hurt she felt; it finally burst out in a terrible scene in Bonn between Charles, Elizabeth and Sylvia, but the details have been lost. The reader's frustration, at such moments, matches that of the principal characters.

The problem with this book is that, having only Charles's diaries, it's hard to understand why Elizabeth Bowen kept faith with this seedy solipsist. The dislocation between their feelings is always apparent. In September 1949 she writes, "Knowing you and loving you has so much changed me that I can't remember what I was like before." A month later, his diary asks, "Oh E, how can I live separated from you?" but, a paragraph later, confides: "I miss my wife. I want her. I am waiting for her. Yet this time of recuperation is quietly, sadly pleasant." You wish for her sake that, quite early in the affair, some time-travelling friend could have pressed into her hands a copy of He's Just Not That Into You.

John Walsh's novel 'Sunday at the Cross Bones' is published by HarperPerennial