A 32-year-old man presents to the psychiatry outpatient clinic with a chief complaint of "I can't maintain any relationships." His wife reports that he is excessively suspicious of her fidelity despite her reassurance, often accuses her of infidelity without evidence, and refuses to confide in her about personal matters. He has had similar conflicts in three previous relationships. At work, he is a competent but isolated employee who avoids team activities and interprets neutral comments from colleagues as personal attacks. He denies hallucinations or delusions but admits to chronic feelings of distrust. His mental status examination is otherwise normal. What is the most likely diagnosis?