There are two possibilities: either it is an instance of solipsism or that of the solipsism syndrome. "Solipsism syndrome is distinct from solipsism, which is not a psychological state but rather a philosophical position, namely that nothing exists or can be known to exist outside of one's own mind; advocates of this philosophy do not necessarily suffer from solipsism syndrome, and sufferers do not necessarily subscribe to solipsism as a school of intellectual thought."
If it is the syndrome then this could be due to looking within too intensely, into the wonderful world of the mind with a diminished sense of care for the person. An individual exists as a person first and foremost, however, a lack of vital social interests and the incentive to actively relate to the life around could induce the feeling that the mind alone is a grand inclusivity of all things, people and places.
You might have seen people stuck in one place, keep on suffering for years in the end. This could be because in their mind nowhere else really exists that they might escape to, a kind of self-imposed imprisonment from which it is very hard to escape. Too much guilt, regret, fear, or any other negative emotion often precipitate this condition. Whereas the arousal of the feelings of love, kindness, compassion etc encourage the mind into feeling more naturally and comfortably towards its world.
"Individuals experiencing solipsism syndrome feel that the world is not 'real' in the sense of being external to their own minds. The syndrome is characterized by feelings of loneliness, detachment and indifference to the outside world. Solipsism syndrome is not currently recognized as a psychiatric disorder by the American Psychiatric Association, though it shares similarities with depersonalization disorder, which is recognized.
Periods of extended isolation may predispose people to solipsism syndrome. In particular, the syndrome has been identified as a potential challenge for astronauts and cosmonauts on long-term missions, and these concerns influence the design of artificial habitats."
You are where you are – A Chinese proverb.