A man leaves his apartment to go to the library, and he turns back several times to make sure the door is locked. frequently, he cleans the apartment even when it is not dirty. the man is likely suffering from:

The man is most likely suffering from the obsessive-compulsive disorder, as the most recognized form is the disorder is the behavior described in the question. The people with the obsessive-compulsive disorder have some thoughts repeatedly (which can be quite exhausting) or feel like they need to do some routines, like washing hands.