Did we talk about this yet? I don't think we did. It's about Glee taking some of the magic-meta and making it explicit.
In Saturday Night Gleever, Finn flat-out tells Mr. Schuester "What I want is for time to stop!" and this is after Mr. Schuester and Rachel, with Miss Pillsbury's help, are heaping pressure on Finn to plan for his future.
Back in Yes/No, Finn already told Mr. Schuester his potential future plans; to join the military. Finn said he was considering it, looking into it, but not 100% sure yet. This clashed with Mr. Schuester's ongoing usage of Finn as his heir/avatar, so he did everything he could to stop it.
Finn wants more time, he wants time to stop, he wants it all to slow down, and Rachel is in GO GO GO GO GO GO GO mode. Rachel knows where she's going. Rachel has always known where she's going. And Finn knows that.
Yeah, he likes her and he's latched on, but she's not shaking him off. And she accepted her marriage proposal after her trickle of self-doubt turned into a tidal wave when Kurt got a NYADA letter before her.
And Finn has these flashes of insight and he knows, I think, why she accepted his proposal.
He spends the last...quarter or fifth of the season constantly testing her commitment to getting married to him. And they flare up and fight but it always ends with her re-affirming that she wants to marry him.
[until that car scene at the train station, when he finally gets her to say she's not 100% sure, and he's been looking for that the whole time]
So we get Nationals! And Finn wants to double their money for their honeymoon, and bought a glass mug to smash at their wedding, and says "happily ever after".
But then he sings "praying for the end of time so I can end my time with you".
SINGING ABOUT TIME MANIPULATION OKAY THIS SHIT IS SO BEYOND EXPLICIT IT AIN'T EVEN FUNNY.
And Rachel gets the lines "I gotta know right now" while he sings "let me sleep on it, I'll give you an answer in the morning" and yes the song is about having sex and getting married.
But it's also about knowing/committing to your future. And so it feels like a call-back to Saturday Night Gleever when Finn was wanting time to stop, and frustrated about his future, and Rachel was all "LOOK AT THESE SCHOOL, no pressure take your time, BUT WE ARE GRADUATING SOON SO THERE KIND OF IS A TIME LIMIT".
So at Nationals, Finn sang about "praying for the end of time, so I can end my time with you" and then in Goodbye he's still testing her commitment to him, with the argument over the chairs, and taking her to the train instead of their wedding, and that whole scene.
And was that whole scheme hella manipulative? Damn yes it was, and I think Hiram and Leroy had a heavy hand in planning it [they wanted to kidnap her from the first attempt at the wedding, after all, and now they're ~waiting in New York~ for her] but as people have pointed out, Rachel still got on the train her own damn self.
[I think getting Rachel to admit she wasn't 100% sure, and then her saying "no one is" was part of what helped her go; her self-doubt was what was keeping her out of New York. But if she can say you don't have to be 100% sure to get married, then why do you have to be 100% confident to get to New York? She can go, even with the self-doubts.]
Finn didn't just set Rachel Berry free from him and Lima.
He set himself free too.