You'll make lots of different kinds of friends in your life. Some friends you'll only know for a summer or an after school class. And some you might know for your whole life.
It's natural for some friends to drift apart. And this is more likely to happen if you and a friend go to a different secondary school or college.
Friendships are normally best when they aren't forced. If there's a friend that you feel you're naturally growing away from, that's okay. You might not have the same interests anymore, and you might make new friends somewhere else.