<s>[INST] my brother has some problem, he is 30 years old ,married ,previously he doubted his sister in law that she told some thing about him ,then doubted another man he trying to spoil his marriage life, after that he doubted  another person,and finaly now his doubt with  his wife that she has many illicit relationship with  others,we know there is no reality likewise he is guessing many things like this, physically also he is obsessed , (talking are constant no anger voice)also his father had some this type of problem [/INST] His understand your concern. This type of auspiciousness and belief suggest delusion. Delusion is fixed firm belief which are not fact, but patient is not able to accept it and not sharable by any mean. Delusion has many types and to reach how it forms and how much it affects personas thought need to evaluate it properly. Delusion is prime symptoms of psychotic illness and if it is associate with other features like hallucinations and disorganized behavior then it suggests diagnosis like schizophrenia. So please do consult psychiatrist and get evaluate his mental status properly. After proper diagnosis and evaluation it will be possible to treat him. Early treatment will bring better recovery. So consult and get well soon. If still have a query then feel free to ask. Happy to help you. Thank you. </s>