After I watched this scene im still confused did or didn't she fucked? for real I read somewhere that they used a body doubles for this scene, but still we clearly see in most of the scenes that is saralisa volm full naked hugging and kissing other guy also the back and her ass looks like her even in the penetration scenes so she might be trully her.
There is a rumor that he trully fucked her but they keep it like secret by telling that they use body doubles.
I don't know about that I'm surely uncertain if she is trully got fucked then this topic should go in Real-sex category but for me it seems that she really got penetrated
Source Wikipedia:In this film the main actors Saralisa Volm and Clemens Schick performed explicit sex like a handjob and cunnilingus, but body doubles stepped in for the penetration scenes.[