Why don't you want to tell your roommate when you go to the library to study? What kind of psychology is this? Is it normal?
Under normal circumstances, everyone may have this kind of psychology. This kind of situation is similar to students studying secretly when they are about to take the exam, but it is understandable to play with everyone on the surface and say that they don't study, but this idea is not recommended. If it is a good relationship, it is better to be honest.