The present research aims to show that emotions and cultural differences in emotions emerge and unfold dynamically during ongoing interactions. During interactions, the flow of emotions in one partner is connected to the flow of emotions in the other partner. In response to distress, romantic partners capitalize on this interpersonal emotion system to modulate each other’s emotional responding. Our overarching prediction was that couples gravitate towards emotional states that benefit culturally valued relational goals: Other-focused emotions such as shame or worry about the partner should play a more central role in Japan, where they are instrumental for achieving culturally valued relatedness goals; self-focused emotions such as anger or hurt feelings should be more central in Belgium where they support autonomy goals. 127 romantic couples (N=254) from Japan and Belgium participated in conflict interactions, which were video-recorded. After the interaction, participants separately rated their emotional experience during video-mediated recall: Every 30s, the recording stopped, and participants indicated to what extent they had experienced each of 12 emotions. We identified attractors using state-space grids and a winnowing technique. In line with our predictions, the identified attractors reflected states of the interpersonal emotional system that support relationship goals of autonomy and egalitarianism in Belgium and social connection and equanimity (or role fulfillment) of the couple in Japan. Additional analyses of the video recordings indicated that motion synchrony increases as couples move into these culturally valued attractor states, suggesting that synchrony may be one of the mechanisms facilitating these emotional states.