A part-time job, study, assignments, homework, and movie evenings (the last on the list) leave you with hardly any time to spare for others including those who once occupied an important place in your life. You realize that your friends from high school are slowly drifting away.
College also puts a lot of strain on long distance relationships (from prior to college). It is easy to get jealous and it is easy for misunderstandings to develop when two of you live in totally different surroundings. People have to adapt to, and eventually get affected by, the environment.