Final answer:
The adolescent girl is likely experiencing peer pressure and social conformity, which leads her to change her behaviors and attitudes to fit in with a new social group, subsequently causing her to distance herself from her childhood friend.
Step-by-step explanation:
An adolescent girl who joins a popular social group and suddenly dislikes her neighborhood friend since childhood is engaging in peer pressure and social conformity. During adolescence, individuals often feel a strong urge to fit in with their peer groups, which can lead them to adopt new behaviors and attitudes, sometimes at the expense of their previous friendships and values. This can be seen as a form of social influence, where the desire for acceptance in a new group outweighs previous loyalties.
Peer pressure can manifest in various ways, such as changing one's appearance, altering one's interests, or, in this case, distancing oneself from a longtime friend. These actions are sometimes a result of the severe need to be liked and accepted by the new peer group, influenced by social dynamics and psychological processes such as displacement or moral disengagement. Factors like cyberbullying, confrontational behavior, and challenging interpersonal relationships also play a role in adolescent social development and can compound the effects of peer pressure.