At first, the verses have an AAAB scheme:
I found my thrill
On Blueberry Hill
On Blueberry Hill
When I found you
The moon stood stillIt's significant that the mood hasn't yet been spoiled by the bridge. The song is still optimistic, with the singer/speaker mentioning a "thrill" and a "dream." But then the bridge provides a turn (like a sonnet's volta) with the lines "But all of those vows you made / Were never to be." After the bridge, the rhyme scheme of the verses changes from AAAB to (with reference to just individual verses) ABBB. Instead of the last line's not fitting into the rhyme scheme that the other lines share; the first line is the different one:
On Blueberry Hill
It lingered until
My dream came true
So we’re apartAt first, the third verse continues with the sadness about separation with "So we're apart," but then it cycles back to the idyllic nature of Blueberry Hill: "For you were my thrill / On Blueberry Hill."
You thought of me still
For you were my thrill
On Blueberry Hill
So the bridge acts as a sort of mirror not only to the rhyme scheme but also to the mood. The first two verses start off optimistically; the bridge shatters the "dream;" and then the third verse, while initially melancholic, achieves some nostalgia by mentioning the "thrill" again, ending the song with a shadow of the optimism present in the first verses.
For years, I knew "Blueberry Hill" only as a Fats Domino song, but it was actually written by Lewis, Stock, and Rose. Among others, Glenn Miller did a version in 1940, which I became familiar with a few years ago. I referenced Miller's version to see how Domino's version compares to it, lyrically at least. Aside from a few word changes*, Fats Domino's version follows pretty closely. The only thing I might take issue with is that Domino repeats the bridge and the third verse, which slightly distorts the mirrored structure that Miller's has.
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*Miller's version has "But all of those vows we made" in the bridge where Domino's has "you made" - a significant change about where the blame is laid. The rest of the changes are minor: in the third verse Miller has "Though we're apart" and "You're part of me still" where Domino has "So we're apart" and "You thought of me still." Domino's repetition of the third verse ends with "But all of those vows you made / Were only to be," which I can make sense of; I'm wondering if it might just be a mistake - either his singing or my hearing.