Co-dependency

Codependency is a psychological condition that makes the person put the needs of others before their own. It originated to describe people in a relationship where they become care-givers to someone who has a substance abuse problem (eg an alcoholic or drug addict).
In a codependent relationship, individuals put the other person's needs before their own, often sacrificing their own integrity and sense of self in the process. Codependency can cause a person to have an overinflated belief that they alone are responsible for affecting the beliefs, thoughts, emotions, and behaviours of those around them.
So codependency is a word used to describe a person who is excessively focused on taking care of the needs of others. This behaviour leads to them having problems in their life because they never do anything for themselves, but they exist to serve their partner. They feel guilty or ashamed whenever they do something for themselves, so they neglect themselves.
Unfortunately this means that codependent people are easy targets for abusive people, especially those who have narcissistic personality disorder. They often end up in relationships with people who have NPD, because narcissists have an extreme need for admiration, which the codependent partner is very willing to provide.
Causes of Codependency
Codependency is often thought to be a result of living with alcoholic parents or other family members who struggle with substance abuse. It is often the result of parentification, when children are not allowed to act like children, but instead have to care for other family members.{cn}}
Codependency may begin in childhood, as children often grow up modeling behaviors after a parent who may have been codependent or in a codependent relationship.
Codependency may also be the result of a traumatic event, whether in childhood or adulthood.
A complex relationship between codependency and narcissism has been established, indicating that the two often go hand in hand, and even sometimes overlap.
While childhood abuse, traumatic experiences, and exposure to narcissistic behaviors of parents and/or partners seem to play a role, it is difficult to predict codependency on the basis of any of these factors alone.
Symptoms of Codependency
There are two main forms of codependence: passive and active. Someone who is passively codependent is more likely to avoid conflict and confrontation, going to great lengths to keep things smooth and not rock the boat. Active codependency is often more manipulative, and an individual may try to push their partner into behaving a certain way in order to fill their own emotional needs.
Both forms of codependence have many things in common, however. Some common signs of codependency include:
Putting the feelings of others above oneself: Someone who suffers from codependence will often sacrifice their own feelings and wellbeing in order to make their partner happy.
''Constrained ability to assert oneself: With codependence, a person will rarely stand up for themselves, and if they do, it is often followed by intense bouts of guilt.
Fear of rejection, abandonment, and isolation: The fear of being alone can be so intense that many behaviors are molded around this. A person may go to extreme lengths to hold on to relationships.
Trouble making decisions without others: A person may be so wrapped up in their partner's needs and wants that they are unable to assert their own.
Need for control: Codependency breeds a strong need to control one's environment and people around them.
Efforts to be the one others depend on'': Codependency can cause a person to feel the overwhelming need to be the caretaker and thus become indispensable to those around them.
References
Psychiatry