My father from past 2-3 years keeps doubting on my mother's character. He always tells us that she had multiple affairs with neighbors and had affairs before the marriage. She is not trustworthy/unfaithful. We are all suffering due to this. Upon researching I found that this some kind of Psychiatric mental illness. I also told my father lot of times to get the treatment from Psychiatrist but he didn't agree. He says that He is completely fine. Now, what should I do? How can I start his treatment?? Is there any way to convince him?? Or are there any tasteless medicine to add in his diet, so that he will be less stressed and later will go for treatment?? Please help. I am at crucial point in my career.