The way these planes are designed, there’s reinforcements in the fuselage that are theoretically, in the case of metal fatigue, only supposed to allow a limited portion of the fuselage to tear away. They’re designed to prevent wholesale failures like Aloha 243 and the BOAC Comet crashes in the 1950s. In this case, they appear to have worked and limited the blowout to one panel.
}:-)4
Exactly
The large rectangular windows were a part of the Comet disasters. That led to the small oval windows we've seen ever since.