We took our two Teenage Daughters on a Cruise around the Canary Islands the Christmas that my DH retired. They were 14 and 16 at the time, and likewise it was on a fairly large shop aimed at families. They hated it, complained about missing their friends, not happy the formal side of things at Evening meal times, or the choice of Films being screened at the on-board Cinema.
They then started to play a game of Hide and Seek in their bordom, and had us worried silly when they his amongst some stacks of sunbeds out on deck and nobody could find them.
The only time they were happy was whilst out on excursions visiting the beaches or doing things like Camel riding or watersports involving speedboats, never again would we ever take them on another Cruise, yet DH and I loved Cruising and enjoyed several more afterwards just as a Couple. I certainly would not go on another one at the moment, and if we did, it would be on-board a smaller ship, where shorter waiting times just to get served at the Buffet, or even to disembark ship in the ports, or the mad scramble for good seats in the Entertainment areas after dinner is less stressful than a City sized Superliner!