Abstract Identity fusion is a synergistic union of the personal self and target of fusion that predicts extreme behaviours on its behalf. Previous work identified that intense shared dysphoric experiences cause fusion with groups, but no research to date has investigated changes in fusion before, during and after a collective traumatic experience. Six repeated cross‐sectional surveys conducted in Spain (2017–2022) (Study 1) showed that differences between sample means in fusion with the country increased during the COVID‐19 pandemic but decreased when the COVID‐19 subsided. In addition, an experiment provided support for these results (Study 2), since making salient the COVID‐19 crisis (vs. neutral situation) increased fusion with the country. Finally, three additional repeated cross‐sectional surveys conducted in Ukraine (Study 3), one month before the war, one month after the war began and eight months later, replicated that differences between sample means in fusion increased just when the war started, but decreased when the conflict turned chronic. The effects were replicated for fusion with a value, democracy. Apparently, dysphoric experiences represent a temporary drive of fusion, but not a maintenance factor.