Previous research showed that supervision during psychotherapy training sometimes includes negative alliance and harmful events. The aim of this study was to investigate how such events were related to failing psychotherapy training. Interviews were made with informants from two separate samples: psychotherapy students who had failed training (n = 6) and supervisors with experience from failing students (n = 6). The interviews were analyzed separately for the two samples with inductive thematic analysis and then compared. The core category for students ('Paradoxical response') indicated that they experienced their supervisors as either demanding too much or nothing at all. The core category for supervisors ('Balancing contradictory demands') indicated that they wanted to fail students who did not live up to expectations but were pressured by training institutes to let them pass. Both students and supervisors experienced distress but it seemed that they were not fully aware of each other's vulnerability. The results suggest that a weak supervisory alliance and harmful events may contribute to student failures, independently of students' actual suitability for psychotherapy.