War is damaging, and the characters in Sun Also Rises are all damaged in some way.  They do not speak explicitly about their various damages, but they are apparent nonetheless.  Jake's war injury affects his life and his perspective on the people in it.  It is clear that there is something between Jake and Brett, but their lives and pasts are heavily influential on their choices, and Brett decides to marry Mike.  It is made quite clear that she does not want to marry him, but Brett copes with the rough life she had with her former husband with alcohol and male company.

There are several common themes throughout the book.  The characters all seem to feel the need to escape.  Many of the characters go abroad for a while, looking for adventure.  They all seem mesmerized by the danger and injury they witness in Pamplona.  These escapist tendencies show the unrest they all feel to some degree.