Some therapists do not “get” the difference between having life problems, and having mental illness (plus, often, life problems). My suggestions for dealing with this, if you are mentally ill and seeking therapy, are:
1) Look for therapists affiliated with hospitals, they tend to have more experience with psych patients.
2) Be leery of anyone who makes a big deal out of “situational” versus “chemical” depression. It’s all chemical; it all happens in your brain and body. Peter Kramer, a psychiatrist who is pro-therapy and writes books about therapy and books about medication, argues that research shows that depression triggered by repeated situational events comes to look no different from depression with a heavier genetic component. It’s just that some people start higher or lower down the slope.
Those who start further down the slope – who some people would say have “chemical” depression – can still be helped by therapy. For example, people who are more prone to depression following negative life events can learn to better anticipate and/or avert those events, and cognitive therapy can help people interpret those events in ways that are less damaging. It’s not always enough, but it can be very helpful.