You have no idea how much I love this scene (ok, maybe you do).
It’s blatantly obvious that Rachel doesn’t want to marry Finn, because it’s the right decision for her. It’s just because she’s a stubborn tiny teenager and she’s dreamt herself away into this magical romantic fantasy world where everything works out as long as she’s got the popular quarterback by her side (nevermind that Finn has no future plans for NY or in general).
And everybody falls for this shit, because everything’s pink and romantic and a teenage dream made of cotton candy (except for Santana who doesn’t care).
And then there’s Quinn who witnessed her mom going down that road and saw where it ends; Quinn who had to grow up way too soon herself. Quinn who admires Rachel and who faught nails and teeth to distance herself from Rachel, because friendship and love or a future outside of Lima is something she would never have. But Rachel helped her see that there’s more to her than just her pretty face.
And just when Quinn has accepted that, Rachel regresses to what Quinn used to be when she dated Finn: a girlfriend and nothing more.
She just wants Rachel to have it better.