People isolate themselves from others for a variety of reasons. Mental health issues such as depression, social anxiety and struggles with abandonment can cause someone to withdraw from family and friends. People who have a lack of self-esteem often isolate themselves against the outside world. Those who are emotionally isolated tend to withdraw socially as do those who have introverted personalities. Sadness can make someone withdraw from friends and family.
Introverts typically isolate themselves from the outside world. Introverts feel drained when in a group setting and energized or recharged when spending time alone. People who have this personality type are not socially inept. They are often misdiagnosed as having social disorders, like avoidant personality disorder. The truth is that introverts simply prefer to be by themselves.
People who experience chronic depression or have a lack of self-esteem tend to shut the world out and withdraw from society. Many people prefer to be alone when they feel bad about themselves or are in a negative state of mind. Those who have recently suffered a loss or a traumatic event may experience a fear of abandonment, which causes social isolation. The most common reason people isolate themselves is because they are dealing with something internal and are not ready to share their grief with others.