Mental health Issues can be a sole problem or in combination with drug abuse. Personality disorders are common, seemingly with an unusual amount of narcissistic personality disorders as compared to other personality disorders such as borderline personality disorder.
Not all odd behaviors makes a person crazy and it's important to distinguish. Accusations about one party or the other having a mental illness is fairly common.
If you do have a mental health situation then it may benefit you to see a therapist for nothing else but to get a clean bill of health. A private investigator who understands psychiatric medications, mental health services, and treatment and diagnosis can help illuminate the issue.