Sometimes, there's this expression on his face, as if he cannot quite believe he got so lucky. I'm not sure what he's seeing when he looks at me, but I want to be that girl.
The narrator describes a moment of intimacy where she observes the expression on someone else's face, hinting at an overwhelming sense of good fortune. This look conveys astonishment and admiration, suggesting a deep emotional connection. She is curious about his perception of her, which fuels her desire to embody the qualities he seems to see in her.
This reflection reveals her yearning to be the ideal partner, one who inspires such awe and appreciation. The struggle to understand another person's feelings while grappling with her own self-image highlights the complexities of love and identity in relationships.