Hello and welcome to Healthcare Magic. Thanks for your query.
I appreciate your concern regarding your girlfriend's psychological problems. Firstly, I would like to mention that a diagnosis of "Paranoid Personality
Disorder" is a clinical diagnosis and has to be done by a psychiatrist
or a psychologist
after a detailed history and psychological assessment. Merely exhibiting symptoms of being mistrusting or extra-cautious may not warrant the labelling of a personality disorder.
In case, a diagnosis of a paranoid personality disorder is confirmed, then treatment is often challenging. It requires long term psychotherapy
or sometimes, medication, and is usually not curable. If you feel that your girlfriend's symptoms are causing major problems between you, I think that the best way to tell her is that since both of you are having difficulties, it would be a good idea to seek professional help to sort out the difficulties. The psychologist or psychiatrist can then assess her to see if she has any symptoms of a paranoid personality disorder.
Wish you all the best.
Dr. Jonas Sundarakumar