This is a terrible combo of soft-porn (without the porn), a rip-off of Genet's 'Un Chant D'amour', and a Mills and Boon romance. Zero erotic tension and embarrassingly bad acting. It reminded me of something and at the end I realised that the same basic idea is used in 'Great Freedom' , another more recent German prison movie from 2021 and the ending is too identical to be a coincidence. So maybe the director of the later film watched this in his hornier youth (bless) but thankfully turned out a near masterpiece of his own. Watch either of these other 2 movies which are both available on this site and leave this in the dustbin of history where it belongs.
This could have been much better. The characters very undeveloped. Difficult to see any real interest between the characters and the ending made no sense.