Well on a positive note people usually start with a psychology of success but since I’m doing this alphabetically I would begin with a slightly pessimistic psychology of failure which will provide significant insights on the psychology of success as success and failure are two sides of the same coin.
The main reason for failure would be fear and even people with knowledge, abilities, resources could face failure if they have unconscious fear. Failure is a part of everyone’s life at some point of time. The psychology of failure would see both the causes and effects of failure from a psychological perspective. It could be explained with a sort of unconscious wish fulfilment theory through fear and we fail when we want to fail and in many cases we are directly responsible for our failures. Let us consider failure in relationships. The failure to have long term meaningful relationships especially romantic relationships could be explained with an unconscious fear of long term commitment and the restrictions that this potentially brings. So if you see yourself as a failure in matters of personal relationships, this may be due to your way of behaving with your partners and the relationship fear that you project on them to potentially disturb the dynamics of the relationship that brings it to an abrupt or gradual end.
Failure in professional relationships could again be guided by fear and the fear of underachievement when you naturally want to excel. Fear in this case is turned inwards and internalized and I have explained this sort of fear in the Psychology of Fear so I will not elaborate here. But this is unconscious and the individual may not be aware of this sort of fear that is the underlying cause of failure. Fear of underachievement and whether one can keep up with responsibilities and expectations could actually even be the basis of fear of commitment in personal relationships. In fact failure in professional and personal relationships are guided by an unconscious fear of responsibilities, commitment or it may be a fear that arises from expectations.