Final answer:
Reactive aggression is linked to unpopularity and social issues among peers due to its characteristic impulsivity and hostility, which contrasts with the positive social effects of prosocial behavior.
Step-by-step explanation:
The main reason that reactive aggression is associated with unpopularity and greater problems with peers is that reactive aggression is characterized by impulsivity and hostility. Reactive aggression, unlike planned and controlled aggression, is often an immediate response to a perceived threat or provocation, displaying little to no forethought, and is driven by anger. Such behavior can cause significant issues in social interactions and peer relationships. For example, someone who responds aggressively to teasing might lash out, thereby damaging their social standing and becoming unpopular due to their unpredictable and hostile reactions. Prosocial behavior, which includes empathy and understanding or cooperation and collaboration, is generally associated with positive peer relationships and thus contrasts with reactive aggression.