Why Kate Middleton Didn't Go to Taylor Swift's Eras Tour With Prince William

A royal source tells ET Kate Middleton 'stayed home' with their son, Prince Louis, and didn't join Prince William and their two other kids, Prince George and Princess Charlotte, at Taylor Swift's Eras Tour London stop at Wembley Stadium for night 1. William celebrated his 42nd birthday at the concert, getting a selfie with the pop star ahead of the show.