Answer:
obsessions
Step-by-step explanation:
Obsessions can be described as consistent and uncontrollable thoughts that preoccupies the mind of an individual, which occurs over a long time and keeps reoccurring. These unwanted thoughts that keeps reoccurring over time can disrupt the daily activities of an individual, and mostly causes anxiety and distress to the individual having it. An individual having obsessions usually engages in behaviors such as compulsive behaviors to relieve the distress.
Stefan's thoughts as described in the question can be considered obsessions.