Ed Sheeran's new album is full of stars, from Justin Bieber to Cardi B

Ed Sheeran at the UK premiere of "Yesterday" in London. Photo: Reuters

Ed Sheeran's new album grew out of the fact that he really didn't need any more alone time.

Arguably the most successful male pop star in the world, Sheeran nonetheless tours like a lonely street busker, with just his guitar and a digital looping pedal to accompany his voice, even when he's selling out multiple nights at gigantic stadiums like London's Wembley.