So you love a person with mental illness. Maybe they have depression, social anxiety, or even schizophrenia or obsessive-compulsive disorder. I can’t help you help them with a specific disorder, but that’s okay. You shouldn’t try to help them with their specific disorder either. You are not a therapist.
That is to say, you shouldn’t be a therapist. Maybe you’ve found yourself falling into that role: You try to help them figure out ways of beating their disorder, you try to ask them just the right questions so that they’ll feel better, or you look up therapeutic techniques and see if they’ll play along. As a long-time sufferer of all sorts of crazy shit, allow me to kindly say: Cut it out.