A 30 year old man has become suspicious that his wife is having an affair with his boss. He thinks his friend is also involved from abroad by providing support his friends tried to convince him but failed to do so. The patient is otherwise normal, doesn't have any hallucination or any other socially inappropriate behavior. The most likely diagnosis is
High-Yield Explanation
Patient is having paranoid delusion, and absence of hallucination, socially inappropriate behavior rules out psychosis. The most likely diagnosis is Presistent Delusional Disorder.