Royal Caribbean have also updated their FAQs in relation to this.
https://www.royalcaribbean.com/faq/questions/onboard-children-sitter-customer-service
Options to have a child free ‘night out’ on the ship:
Invite a group of people, and you might be able to get away with them baby sitting one night.
Make friends with another family onboard with young kids and take turns in baby sitting each night.
Post a note on the notice board looking for responsible people to babysit.
Ensure you choose a ship with a nursery and book a place ASAP for an evening session. This is for a charge of $8 per hour from 6pm-midnight.
Happy cruising! 🚢