Is it normal become attached to group of friends

I don't even know how to start this so many things are running through my head I feel crazy. Okay so I have moved around a lot always made friends easily and never had a problem moving to another school, but I move to this poor school expecting the same thing to happen, a years gone by and I think this time these people are so real and they care mind you it's only a few from a large group, I haven't told anyone I am moving at the end of the year. I don't know what I'm waiting for, and I have done the whole "I'll still see you, things won't change" with so many people and I know that's how it's going to turn out, but I dnt want it too, I wanna be friends with these people for a long time and I need to move because I need to follow my career in sport and staying and I won't be able to do it no way, and I never trust anyone why is it I feel I can know these people my whole life why can't I walk away?