Question

When marcus rides the elevator at work, he always stands facing the back of the elevator car. although this goes against standard social practice and makes his coworkers uncomfortable, it is more likely to be psychopathology if it is?

Answer 1

It is more likely to be psychopathology if it is impairing good daily functioning.
If Marcus doing this is not impairing his daily functioning, then it won't be considered psychopathology, but rather something weird he does that makes other people feel awkward. However, if this is causing him troubles, then it becomes psychopathology - a mental disorder.