Want to file for divorce wife is having a mental disorder

My cousin is married just married 2 months ago .His wife eloped, she typed a watt Sapp message stating she didn't like the boy as he is having spondylitis and wrote a letter that all convinced her to get married ,but she didn't like the marriage and mentioned the names of few relatives in her letter who convinced her for marriage. Her parents filed a missing complaint in the police station with the statement of in-laws stating that she is mentally upset. How can my cousin file a divorce. He is in U.S. Just stayed 15 days together after marriage. we took her to psychiatrist after the first night. Doctor identified she is having border line personality disorder .She mentioned that she wants to trouble everyone as she is angry as my cousins parents took her to psychiatrist counseling .How we have to proceed in this case. Marriage taken place in Hindu temple. Police still couldn't trace her.