The Paris Wife could easily be understood as a reflection of Ernest Hemingway, the greatness of his craftsmanship, the despair of his tragic downfall into suicidal depression, and the vibrance of his indulgent life—but to interpret the book as fundamentally "about" Hemingway would miss the point entirely. The novel is actually about lost love and the tragic situation of the woman in the background to his early life.
Hadley is older when she meets Hemingway, but there is no indication that she believes she is more mature. In fact, Hemingway's charming, out-going personality often leaves Hadley feeling like an outcast, a tolerable person that doesn't quite fit in. In this way, the story offers the reader an opportunity to look past the glitz and glamour of Hemingway's character, and to look into the person Hemingway failed to see.
What does a person see when they look at the Paris wife herself? The novel depicts the diligent, sincere, loving attitudes of a woman who simultaneously adores her husband and also wishes he could become healthy and balanced. Perhaps what the reader learns most about Hemingway is that his suffering and his blatant narcissism are entwined, like a genius who knows he's exceptional but doesn't recognize that it's a gift. This means that when the Paris wife offers real true love—the kind of love that is willing to confront and challenge—Hemingway resents her honesty and moves away from her, toward people who will blindly support him.
In the long run, Hemingway's time ends with suicide. Perhaps another thematic reading of the story might be, "Try looking at the background characters in life. Perhaps there is a great source of true love, but you're too self-involved to notice it and be thankful." That is not to say that Hemingway was a villain, he wasn't; he was a deeply troubled man, but no doubt, his time on earth could have been made better if he learned what the Paris wife was trying to teach him: Real love takes hard work and humility.