You don't have to do anything you think is immoral or unethical. I would suggest caution being too open in commenting on that new hairstyle, when honesty will adequately do. Never does a patient have more motive to lie to you than after taking a drug with suicidal or recreational intent. The distinctions blur between suicidal and recreational use. Greater tolerance is the duty of him or her with the greater insight.
Good information can come from a bad source.
Just because you love someone doesn't mean you should marry him or her. Nothing heals like a hug. - anon. Beware lest you misinterpret acquiescence as agreement. No fool deserves to be told. Self-discovery works better.