Rachel wonders what she sees in Finn. He's the regular jock you'd find at any high school. He's hurt her more than once.
Then she puts her head on his shoulder, and it feels so right.
She forgets about losing regionals, she forgets about her mother not wanting her, and Jesse. She just sits, and can't help but be overcome by a sense of peace.
Because he's Finn. Yes, he is a jock. He plays decently at football and basketball, but still shines. He's had the weight of the world on his shoulders but has bared through it all. And his voice. The first thing Rachel noticed about him was his voice. He was so inexperienced but so naturally talented that it took her breath away.
When she has her doubts about him, she thinks about how he'd stick up for her, how he threatened Jesse for her and she remembers why she's so irrevocably in love with that boy.
So she sighs a happy sigh, smiles, and snuggles closer to Finn and listens to the words Mr. Shue is singing.
Somewhere over the rainbow
Bluebirds fly.
Birds fly over the rainbow.
Why then, oh why can't I?
And she feels, with her head on Finn's shoulder, their hands intertwined, that she's flying over her own little rainbow.