Table 5 Quotes on group experience before (T0) and after (T1) treatment

T0.2.1 Interacting in the group (63)

 “It’s the exchange with other patients who have had a similar fate or have made similar experiences. You get to learn about new perspectives that you haven’t encountered or haven’t been able to encounter before.”(F)

T0.2.2 Community experience and feelings of belonging (42)

 “When you are not feeling well mentally, you are stronger in a group setting, I think. The incentive and the motivation are greater. Also, you receive help outside of the therapy sessions. You don’t know what kind of people you will meet there, perhaps you will find new friends. People, who can support you. I think it is really intensive to do group therapy together with someone.”(U)

T0.2.3 Learning through interactions in the group (28)

 ”[…] … and you can get into contact with other people. On the one hand, in order to differentiate, on the other hand to set your boundaries and to engage with others, telling them that here is my space, my boundary, and there is the other person’s boundary. This would help interacting with other people.”(Q)

T0.2.4 The challenge of opening up in the group (79)

 “You would like to be strong and not show any weakness, because that would make you seem vulnerable and could lead to others hurting you. And the more people know about it, the more difficult it gets. This is a disadvantage of the evening clinic because there you have to open up to a group of 6 people as well as to the medical professionals.”(F)

 “That I won’t be accepted into the group or that I will have conflicts within the group.”(S)

T0.2.5 Engaging with the topics of the other group members (11)

 ”[…] that I might find it difficult to open up and deal with the problems of others.”(K)

T1.2.1 Interacting in the group (107)

 ”Yes, you may just see other courses of action or that people deal with them differently, other problem-solving possibilities are pointed out that you may not have thought of yourself yet.”(H)

 ”Yes, that several things have changed, that some things were different in the past, that I have become more open, that I am looking for more conversations, especially if something disturbs me, that I then speak about it, for example.”(F)

T1.2.2 Community experience and feelings of belonging (215)

 ”And so it is good in this group that you see that everyone is struggling with these problems and that also creates the incentive to develop there.”(C)

T1.2.3 Learning through interactions in the group (64)

 ”And then also the interaction in the group and with the other patients, that’s also something that I have a hard time with, with social things, social interaction and so that was actually such, yes, such a good test field for it.”(N)

T1.2.4 The challenge of opening up in the group (74)

 ”Was it harder for me to open up, well, to talk about my problems because I thought the other -, the problems of the others are more important.”(R)

T1.2.5 Engaging with the topics of the other group members (34)

 Because at that moment I pushed myself all, all the way back. And I didn’t know how to deal with other people’s problems either, so it must have taken me a week to even know how to deal with them.”(W)

T1.2.6 The challenge of a semi-open group setting (36)

 “And that the group members were, uh, constantly changing, that made me really, uh, even harder.”(S)