[link to original on tumblr]
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After the line "I'll remember all the little things we've done" (it's the same in both iterations of the bridge), there's a diatonic descent in C major from the G above middle C to the G below middle C and then up a whole-step to an A. (I think it might be doubled an octave higher too.) That whole phrase seems to represent "all the little things."
The next two lines in the bridge are different in each instance, but the musical representation for each is the same. First, there's "Can't she see she'll always be the only one / Only one," and second there's "She'll remember, and she'll miss her only one / Lonely one." After each of those "one"s, there's a single G note as a representation of that singularity.