Thinking about one’s ex-romantic-partners is typically regarded as detrimental to people’s current romantic relationship. However, thinking about past events and relationships in a nostalgic way is suggested to result in beneficial outcomes. In the current work, I examined whether nostalgia for an ex-partner influenced people’s perception of current relationship quality and the underlying mechanism. In Study 1, I found that recalling nostalgic events about an ex- partner led people to report higher relationship quality, compared to recalling day-to-day ordinary events. In Study 2, I improved methodological limitations of Study 1, and further showed that recalling nostalgic memories about an ex-partner increased perceived current relationship quality, compared to neutral memories that either involved or not one’s ex-partner. Additionally, I found that the positive effects of nostalgia for ex-partner on perceived current relationship quality was mediated by growth mindset.