Somehow that just doesn't land the same.
I fear that a modern colloquial rendering would disappoint yet further:
our besties tune"Our secret song"
"Our shared song" is looser, though context helps.
"They're playing our song" still captures the timeless feeling. But is wrong for the poem.
I’m surprised how much I’m enjoying it. And I can’t believe I have 195 episodes left.
Same number of syllables.
Maybe “Song of just us two”
Like it’s common to hear “You two better stay out of trouble”
Or “it was us two in the apartment alone…”
Or “them two are pretty good together ”