Friendship means different things to different people. As you grow up and get older your friends will grow up and get older as well. That doesn't mean that they are not your friends what that means is that you will not text 24/7 anymore but rather once a week or once a month. The times you can connect will be even better because you will be able to talk about so much in the short amount of time you talk together.
You will not always see each other every day or even every other day but maybe once a week or once every few weeks. As your life gets busy so does theirs. As you start to deal with different issues so do they. So the time that you guys do have together means so much more because you guys will have each other's full attention!
You might feel depressed that the people you thought were your friends never text you back or don't want to hang out with you. That is not true because they are busy and dealing with their own things. They do want to be your friends, they will text you back, and yes they do want to hang out with you. You guys both have busy schedules so you are not able to talk and hang out all the time anymore. The times you are able to mean so much more and you guys fall back into old routines.
It can be hard and can feel like no one likes you-THAT IS NOT TRUE!! If you feel your friends don't like you then talk to them because it is most likely your anxiety getting the best of you. Yes, this happens-it recently happened to me and when we finally were able to hang out together I felt so much better and realized that they do love me and are my friends.
People are busy and have things to deal with which means that they might not always text you back and might not always be able to chill but when they do it means they do want to talk with you.