In the short stories, "Death By Landscape" and "To Room Nineteen," both protagonists are isolated by the circumstances in which they find themselves, but the isolation is for very different reasons.
In "To Room Nineteen," Susan is isolated because of the time in which she lives (the 1960s) because she has no friends, her husband is cheating on her, she has no idea who she is as a person, and society provides no avenue of escape for her. She is totally alone and does not have any idea how to cope with the circumstances of her unhappy life.
In "Death By Landscape," Lois is also isolated in that she is a widow, and she does not have a husband to lean on or look to for support. In Lois' case, however, she is haunted by the past--not the present--and a terrible experience that has had a hold on her for many years.
In this story, Lois did have a friend and their connection grew over the years that they attended summer camp together. During their last year at camp, the girls went on a canoeing trip, and Lois and Lucy separated themselves from the rest of the group. Lucy left Lois for a minute, Lois heard a scream, and Lucy never returned, neither was her body ever found. Without any valid reason, the head of the camp, Cappie, accuses Lois of pushing Lucy [off a cliff].
In both stories, our protagonists face the conflict of man vs. man. Susan is isolated in the midst of her problems, and her husband is not there to support her while he carries on an adulterous affair. Susan also faces man vs. society, when she is forced to keep up appearances because that is what society expects.
Lois' conflict with "man" is in the form of Cappie's accusations of Lois' part in Lucy's disappearance/death. However, Lois is able to rationalize Cappie's behavior when she reaches adulthood, knowing that the woman simply needed someone to blame.
The major difference it that Susan gives in to her isolation and distress, while Lois learns to deal with it as best she can.
Although Lois never quite recovers from the experience, she finally accepts that part of her was left in the wilderness when Lucy disappeared, and Lois chooses to move on.
On the other hand, Susan can find no way to put the events in her life into a perspective that allows her to cope, and at the end of the story, she takes her own life.