You may not be passively depressed, rather you maybe expressing emotions and behaviours that indicate depression. Such strong emotions are felt after a huge change in life. It maybe difficult to cope, therefore you feel aloof or experience mood changes. This could also be hormonal. Another cause of mood changes or in your case depression is because of a lot of pilled up stress. If you don't usually speak to people about your problems it can cause sudden depression and aloofness. If you have had a recent conflict (with friends maybe?) and haven't resolved it yet. It could cause your annoyance which feels like aloofness and depression.

Firstly try to understand your depression level . So that you can understand highly loaded factors and resolve the conflicts accordingly.