Adolescence is marked by rapid biological and psychosocial changes that profoundly impact parent–child communication in order to reorganize responsibilities and move toward a more egalitarian relationship. Therefore, our primary objective in the present study was to explore the influence of changing conflict frequency and intensity on the perceived level of closeness between parents and adolescents, considering the perspectives of both parties involved. Using 10-wave longitudinal data with measures of parents (n = 17,005) and their children (n = 15,841) aged seven to 16 from the German Panel “Analysis of Intimate Relationships and Family Dynamics” (pairfam), the present study used fixed-effects models to address the research goal. The findings indicate that, for parents and adolescents, an increase in both conflict frequency and intensity corresponds to a more pronounced decline in closeness. Higher levels of initial closeness when the participants entered the survey resulted in milder decreases in closeness when conflict intensity was higher, a pattern observed for both parents and adolescents. Regarding conflict frequency, no impact of initial closeness was discerned among parents, while an opposing effect was found among adolescents. These findings shed light on changes in parent–child communication during the transition from early to middle adolescence, underscoring the need for further exploration of the closeness–conflict association.