It is controversial whether the delusional disorder, erotomanic type, can be consid- ered as a primary disorder. Most cases diagnosed as primary erotomanic delusional disorder are in fact secondary to another disorder, mostly schizophrenia or bipolar disorder. Yet, true cases of primary delusional disorder are described. A close look at these cases reveals that instead of a delusion in strict sense the erotomanic disorder is a disorder of attachment. The difference with falling in love is merely gradual. Yet, there can be psychotic complications. A passion can drive a person mad.