Dealing with Transition

I have a student that has become increasingly disruptive and defiant. I have a pretty good relationship with this student and am sad to see this change in behavior. Now, this hasn't always been the easiest person to get along with but I do like this student and want them to be successful and happy, and right now it seems like the first is being sabotaged and the second is in battle with a growing anger.
This behavior could be a defense mechanism to create distance in order to make leaving easier. This student, along with all the other 8th graders, will be leaving the safety and familiarity of the school they have spent three years in and have rose to the top of the middle school food chain in and entering High School as freshman. Leaving is difficult, but this behavior is making the now difficult.