Slop.

Yeah literally none of Rudy's relationships are healthy or ok. The anime did kind of do Sylphie dirty compared to the ice cold veteran who had to grow up way too fast she is in the books (in the anime she's way too fluttery and flustered all the time, vs the books where she's explicitly supposed to be the shoujo Prince archetype), but her relationship with Rudy really is not healthy; the early books even had a sequence of what was basically Paul turning to the camera and explaining over a page or two exactly why grooming and codependency are bad and unhealthy and how it would be extremely toxic and harmful if Sylphie were codependent on Rudy, leading to the plan to split them apart so they could each grow and be their own person. Then there's the inverse with Roxie whom he unironically worships as a literal god and who took advantage of him when he was a complete wreck of guilt, goaded along by Sylphie's shitbag grandmother. Nothing about either direction of his relationship with Eris is healthy or ok either, neither the bit that the anime covered nor what will happen presumably at the end of the next season or in the one after that.