Kevin, please don't worry!
We have been cruising with Carnival for 10 years. My children are spoiled from it. They've never complained once that they want to try a different line. They've met great friends and they've formed lasting friendships from these encounters on-board. My youngest daughter has literally a list of girls that she e-mails and sends Christmas cards to every year.
When we board the ship, the first thing our daughters' do is find out the time and place for the first teen get together. After that, they are so busy doing their own thing. They just check in with my husband or myself. Much of their at-sea days are spent on the waterslide with friends.
We only request that we eat our 3 meals together as a family. Other that, they do their own thing. Unless, of course, it's a port day. Then, again, they are with us.
Please relax, don't worry about things and enjoy your cruise.
Post when you get back home. I'm betting you're going to say you worried over nothing.