Most people that you choose to have in your life are chosen because your lives or you as people align in some way.
It could be a similar taste in music, studying (or have studied) the same subjects, enjoying the same leisure activities, similar mindsets and worldviews or maybe you share the same aspirations.
Whatever it may be, when the base of your connection shifts it is likely that you may change your mind about having the person in your life.
Granted you will have built up a connection based on other things over time but when the core bits of you and a person no longer align, the relationship may no longer make sense.
This sort of thing quite commonly occurs once you begin to really figure out who you are and what you want in life. Perhaps the people you used to party with don’t really fit with the life you’re creating. Maybe your corporate aspirations clash with the aspirations of people around you to the point of causing disagreements.
Despite how it may feel, it’s a natural thing for relationships to change. It’s much better to allow things to be than to restrict your development or the development of someone else because you’d rather hold on to something that was never meant to last.