Well, thank god we have your completely objective opinion on the inner workings of the Dortmund squad.
Yeah, Roman Bürki and Julian Weigl sure seem miserable, laughing and fooling around on multiple videos and pictures. Gonzalo Castro at least accomplished something what Ciro "whiny bitch" Immobile never did: having dinner with a teammate, namely Neven Subotic. Henrikh Mkhitaryan also lives with the terror that no other player is into chess as much as he is. Players like Kevin Kampl, Mats Hummels and Nuri Sahin have at least enough pity with him to accompany him to games of the youth teams and second squad. Meanwhile P.-E. Aubameyang had the same language barrier to overcome, but weirdly hit it off instantly with his buddy Marco Reus to the point that they are now nearly inseperalable. Shinji Kagawa is very close to Ilkay Gündogan, so much that the latter even traveled to Japan during his vacation to cheer for the former in International games.
I could probably dig up even more if I would be really into all that twitter, facebook or instagramm stuff of the players, but the point is that the public only sees a very restricted view on team dynamics.
What I do know is that I could list interviews of more than a dozen players, including former ones after they left, who had nothing but praise about the integration and support inside the team.
One player, who searches for so many things to blame but not himself, is not going to change my opinion if the vast majority says otherwise. Integration is always a two way street and if one individual fails at it while dozens succeed, then I rather take a look at him than the group.