“Pop mutates with the times and tech, artists go in and out of vogue, but for many pop stars, the song — and the narrative — remains the same. First albums teeming with ambition and vigor give way to followups that grapple with fame, success and perhaps excess — which in turn pave the way for the inevitable newfound-maturity phase. For Ed Sheeran, that moment arrives in the very first line on = (pr”