This could also be an affect from his childhood abuse, where his father had beaten him and his mother when he came home in a rage. Only once in the movie did it really show Will Hunting getting angry to the point of insanity (if it could be called insanity), and that was when Skylar asked him to move to California with him. He stated no, and grew upset with her. She then told him that she loved him, and he lashed out at her with furious words, hurtful words, and the truth about him, that he has no brothers, that he is an orphan, and that his father physically abused him when he was younger. It’s the anger that pushes him away from Skylar and causes her to go to California without him, causing him to not have to deal with someone trying to get close to him, to learn about him, and to attach to him anymore, the same thing he did in all of his other relationships; make sure that no female would want to stick around. Throughout Good Will Hunting, Will Hunting experiences many different psychological experiences, such as some stages in Post-traumatic Stress Disorder and the stress of having to grow up with an abusive family, never having the chance to attach to somebody he cared for and to never be able to trust anybody. However, with help, Will learns to overcome these psychological obstacles and chases down his dream girl, Skylar.
References
Brown, J. (n.d.). The Effects of Child Abuse on Young Adults.