I suppose my moment was after our second date. The first one was to a formal dance, so we really didn't get close and were too nervous to "be ourselves." The second was to a picnic, and we had great fun. We were just 15 years old, and being so close to her, seeing her smile, captured my heart.

The question seems to relate to a typical romance. But in my case, it was a wild crush on an Aunt which she did not discourage.