This is an outstanding novel, a fictional examination of Dickens marriage and affair. Even the names are changed, and, as the author says in her introduction, events are rearranged to suit her narrative. But that's OK, in fact, it probably makes for a much better novel.
What's important is that it rings true and convincing, which is a testament to the author's skill. After finishing the novel, we can believe that it happened this way, and that we have had a glimpse of the real Charles Dickens.
It's not a flattering look at his personal life. The novel begins with his death, the the protagonist is his estranged wife. Dickens kicked her out of his home, denying her access to her children, ten years before he died, so that he could carry on an affair with an actress young enough to be his daughter. They didn't teach that in school when I was a kid - only recently have details emerged about Dickens personal life.
The author creates a convincing world for her fictional author, his wife, and his mistress. Highly recommended.
Link to Amazon: Girl in a Blue Dress: A Novel Inspired by the Life and Marriage of Charles Dickens