It's not always easy, keeping your friends throughout chapters of your life. As I transitioned into a college freshman, I was one of the lucky ones. I managed to keep my high school friends close. Despite the statistical force in our way, we've managed to stay a close group. I've known some of the people in my group since kindergarten!
We fell apart a few times. Some people from the group leaving, some being pushed out. Some of our friends haven't rejoined the group; the core group has stuck together through thick and thin, though. There are about seven people in our group, more or less. My friends have had my back, and I don't intend on ever losing them. We've all managed to stay so close through having a group chat. Sometimes we're not all active, but luckily it keeps us all in contact enough to keep our group tight. Outside of the group chat, some of us actually go to college together. The rest of the group is either very close or very far, but we manage to spend time together at least once a month, or every few months.
The key to keeping those you love close is to maintain contact. Whether you're feeling introverted or upset with someone in the group, all of that will eventually dissipate. Would you rather work through the problems or lose life-long pals? I maintain contact through the group chat, through Snapchat, and trying to spend physical time with my closest friends every week. I feel upset or guilty when I don't have the time for them or I don't have time to talk in our chat. I'm always reassured and eventually, the feelings of guilt are replaced with feelings of happiness and closness that only lifelong friends can supply.
I hope I can always mantain these close friendships, through thick and thin.