Because the royals have just arrived at the castle and some need some more time to adjust. There will be no welcoming ball.

However. All royals do agree that all of you deserve a moment with them and your fellow selected. They just couldn't agree on what to do so they split up.

The princesses will have a tea party at the water.
(Ofcourse this isn't everything! Alcohol will be served.)

And the princes are going on a picnic.
(Ofcourse this isn't everything!)