Over time relationships with these people tend to deteriorate. The constant neediness and dependency at some point will never be able to be filled. The analogy of a deep hole that a person continues to pour dirt into but that can never be completely filled describes the emotional investment a person has in relationships with these people. This occurs to the point that the lives of the people around the dependent personality are consumed only to the point they are willing to let it consume them. When the break occurs the dependent persons life has in turn become the life of the other person. The dependent person has difficulty in letting the relationship go. The dynamic of the relationship is one where in a dysfunctional way the two lives become one. The dependent person does not understand why the supportive persons are leaving them and always feel as if they did something wrong and if that could be changed that everything will get better.
The reality is that everyone (other than controlling persons) can only invest a certain amount into someone else until it begins to consume them. And when they leave the relationship it creates a vacuum because the dependent person suffers the loss of the relationship and the loss of what they became. This only increases the feelings of failure over and over. It is not unusual that in the times of desperation the dependent person will threaten suicide or break all ties with their support system in reaction to the failed relationship.