Friendship is a beautiful thing, and we all make friends at one point in life. Like you said, friendship just happens, but as you grow older, you'll see that you don’t have as many friends as before. That's how adulthood is; we're more focused on our lives and future.
I've always been the type who loves making friends, but I never had lots of friends. Later, I learned to be by myself and not feel hurt about not having many friends. Now, it doesn’t even bother me at all