Mine was when Kang Min Ki mentioned that he heard his name from the female lead after a long time. It was either that moment or when he saw her on the bridge in his first life when FL was dying he looked at her with eyes that were longing for someone. And, when the female lead asked him if they were each other's first love in her first life, he seemed shy and denied it. However, the way he looked at her made me think otherwise. It was the first time I experienced a 'support lead syndrome.