Ellen Glasgow (1873 - 1945) wrote during two overlapping periods, the Realist literary movement (1820 - 1920) and the Existentialist movement (1850 - present), and one can certainly see traces of both in her final novel In This Our Life, published in 1941 before her death. However, Glasgow was once quoted as calling herself a "verist" rather than a realist. A verist strives to represent truth in literature, including all things distasteful (as cited in eNotes, "Ellen Glasgow Long Fiction Analysis"). She argued that "the whole truth ... must embrace the interior world as well as external appearances" (as cited in "Ellen Glasgow Long Fiction Analysis"). As a verist, she particularly sought to portray the South as it truly was since it had been severely changed by the Industrial Revolution and was no longer the romantic vision she felt other authors portrayed it to be. She felt it was a society run by an aristocracy that needed to face the challenges of change.
Hence, in one sense In This Our Lives can be seen as a verist novel striving to portray the South in all of its focus on materialism and the social decay ensuing. We particularly see materialism portrayed in the female character Stanley Timberlake, who was about to marry attorney Craig Fleming but instead begins an affair with her sister's husband Dr. Peter Kingsmill. When her sister, named Roy, divorces Peter, Stanley marries Peter instead. Stanley's choice to start an affair just before her wedding day shows her questionable morals; she values fulfilling her material needs above anything else. Such materialism can be seen as a byproduct of industrialism because industrialization led to an increase of wealth, which leads to favoring material possessions. The divorce can also be seen as a break from traditional values held by the South, which is also a result of industrialization.
However, as a verist, Glasgow also has a tendency to portray the existentialist philosophy popular in those days. Existentialism was founded by Soren Kierkegaard and teaches that "we are thrown into existence" in a world we have no ability to control; we have no ability to control who we are and what we do (Saint Anselm College, "Summary of Some Main Points from Sartre's Existentialism and Human Emotion"). The belief in a lack of control for some thinkers leads to a sense of helplessness and hopelessness. Existentialism is portrayed all throughout the novel in all of the negative and uncontrollable things that happen to the characters, such as Peter's depression, Stanley's alcoholism, her hit and run accident, and her death at the end.
University publications are going to be the best source for an analysis of In This Our Life.
Glasgow is an author who does not get the appreciation that she probably deserves. Glasgow does not receive the amount of attention that that other Southern writers--Margaret Mitchell, William Faulkner, Eurdora Welty, Flannery O'Connor or Tennessee Williams--receive. Glasgow is revered for her talent in university circles. This is going to be where analysis of Glasgow's work will be present. However, finding an abundance of analysis of her work is going to be difficult.
There are some locations online where analysis of In This Our Life can be found. These sites have been included below. From what I could gather, Dorothy Scura has done some solid work on Glasgow and her Pulitzer Prize winning work. She has been able to put together contemporary reviews and analysis of In This Our Life. Scura has also written an analysis of the novel itself. However, most of the links below are proprietary and will require paid membership to online organizations in order to access. Another source would be James Southall Wilson, who is the Edgar Allan Poe Professor of English at the University of Virginia. He has composed an analysis of In This Our Life. He focuses on characterizations within the novel that mesh with the vision of the changing South. Wilson's analysis brings out greater complexity in a novel that is already filled with intricate and profound sadness.