I don't think Charlie does this on purpose. I don't think he means to cause upset, but when you are someone who is friends with everyone, you are gonna bits of info from all sides and that's when it becomes a danger to Charlie. Not being sure who else knows what he knows, so he is in danger of saying the wrong thing to the wrong person. But sometimes it's obvious that certain info is not shared throughout the house.
I mean come on Charlie! Why would Bea and co tell Noirin & Issac about their time in the Diary Room? How dumb can you get?
Charlie to Noirin: "I thought you knew!"
Oh yeah Charlie! Bea told her,....D'oh!