Positivity resonance, a collective and caring affective state that strengthens social bonds, is studied mostly in the US, leaving cultural variation unexplored. Considering US vs. East Asians, the inner value perspective would suggest that values of independence vs. interdependence shape relational experiences and predicts that East Asians would experience higher levels of positivity resonance than European Americans. However, increasing evidence on social behaviors has shown more support for a socioecological perspective that suggests that where ingroup ties are ascribed (low relational mobility), relationship maintenance behaviors are unneeded, whereas where relationships are chosen (high relational mobility), relational maintenance behaviors are functional. Across three samples collected through online platforms (one from each country, N = 4125), we found that East Asians had lower positivity resonance (collected through the Event Reconstruction Method) than European Americans, with both weak ties (MD = 4.15, p<.001) and strong ties (MD = 8.07, p < .001) and that, consistent with the socioecological perspective, relational mobility (self-report) mediated the difference for strong ties (indirect effect=.016, 95% CI = [-.021, .035]). The findings suggest that valuing harmonious relationships is not equal to more efforts to strengthen social relationships and demonstrated relational mobility as an important mechanism to understand positive emotional processes and relationship maintenance behaviors with strong ties.