From couple disputes to interstate tensions, conflicts are an inevitable part of life. The aim of this thesis was to investigate how emotions and emotion regulation interventions change conflict-related social relationships. We conducted four empirical studies that examined compassion and schadenfreude in conflict and tested the effectiveness of compassion training and reappraisal training in conflict. A fifth study investigated the causal effects of sleep loss on conflict resolution. Taken together, our findings highlight the central role of emotions in different conflict-related social relationships and in different phases of conflict. Our work also emphasizes the ability of compassion training to enhance social connectedness in ongoing conflict-related interactions. Finally, our results showed a causal impact of sleep loss on conflict resolution by modulating affective responses. Overall, this work contributes to a better understanding of emotions in conflict-related processes and provides several avenues to build more tolerant, cohesive and compassionate relationships.