A lot of the reviewers are applying US legal views to European characters. The age of consent in much of the world today is considerably lower than it is in the US. Never mind that in the not too distant past, including in the prudish US, it was far lower than it is today. "Oh no, a 17 year old boy had sex..." is just a distraction from the film is overly long, overly boring, and filled with other plot holes. That's the *real* issue here and it has nothing to do with birthdates, real or imagined, of the actors involved in this near train wreck of a film.
The constant time travel forward and back to make an almost non-existent story arc seem more complicated than it really is doesn't add drama, or intrigue. It's just annoying, and makes you feel like you need to keep notes at times. Next up, the sound track, which is often out of some teenage Disney movie, instead of a thriller.