I hear how worried you are that he's cheating. My first question is could there be any reason why he would have to go to his college after the term has ended. You say the college is closed. Does this mean that no activities are going on at the campus? Are the gates locked? In other words, is it possible that he could be doing something at college other than taking classes?
He said he had to go to college, but he didn't say he was going to classes! So before you assume he's lying, you need more information. This being said, you still have to trust your instincts. If you have the feeling that he's cheating, you have to listen to your gut and honor that. Obviously you don't want to accuse him outright. So I think you would be wise to get more information.
Ask him what he's doing at college and let him explain. If the answer makes sense, then see if your feeling of doubt passes. If it doesn't pass or if his explanation doesn't feel right, then discuss your feelings. Tell him that you're wondering why you've begun to feel insecure about your relationship. After you ask this open-ended question, see what he says.
You might also talk about the distance between you and how it contributes to your feeling of insecurity. You might tell him that you've been all right with it until recently when he didn't want to see you. Ask him if he's happy with the relationship? Ask him how he feels about being exclusive with you. Ask him to talk more about why he might not want to see you more (fear of getting too close? Feeling crowded?)
Get to understand what feelings are going on inside him and how the feelings are connected to the distance between you. I've given you a plan for opening up the discussion. Once all the feelings are on the table, you will have a much better understanding of where you stand with the relationship.