Fluctuating together over time: Within-dyad life satisfaction dynamics in parent-adolescent dyads.

Empirical research has consistently documented positive associations between parents' and adolescents' life satisfaction. However, most evidence is based on between-family designs, leaving within-dyad dynamic processes poorly understood. Using six annual waves of data from 2243 parent-adolescent dyads participating in the Korean Children and Youth Panel Survey (ages 14-19), this study examined whether parents' and adolescents' life satisfaction fluctuates together and predicts subsequent changes in one another over time. A random intercept cross-lagged panel model was used to disentangle stable between-dyad differences from dynamic within-dyad associations. Results revealed positive between-dyad associations, indicating that parents and adolescents with higher average life satisfaction tended to belong to the same dyads. At the within-dyad level, parents' and adolescents' life satisfaction co-fluctuated positively across adolescence. In addition, small but reliable bidirectional cross-lagged effects emerged, such that higher-than-usual life satisfaction in one family member predicted modest subsequent increases in the other family member's life satisfaction. These findings suggest that parent-adolescent well-being reflects not only stable between-dyad associations but also modest reciprocal influences that unfold over time within families. The study highlights the importance of distinguishing between-dyad and within-dyad processes when examining intergenerational well-being across adolescence.