So, apparently their nation has long abolished the death penalty in favour of exile to a subtropical island where the criminals are left completely to their own devices (they basically all stick to subsistence while constantly avoiding others out of suspicion, eking out a miserable existence — that's where the queen and princess are sent after being stripped of their royal rank). For Robin, his abuse of his magic is too dangerous, so its sealed away, which means he can't be exiled (because the seal requires some kind of maintenance). Beltrand and Latrice decide that such a pervert will suffer most in a strict monastery: turns out, not only does Robin consider any place without women to be a fate worse than death, he's such a conceited pervert that he's convinced that the monks earnestly attempting to reform him are trying to shag his ass.
As for the baby, his parents didn't love him — even the ever-indifferent Leonard cares more 'cuz he's willing to intervene if something goes significantly wrong. Beltrand and Latrice want to help him, but note that supporting the boy in any official capacity is not an option (both politically and from the angle of the boy's mental health: growing up in the public eye, all royals are, as the son of such criminals would not be healthy). So they allow his wet nurse, who loves the boy as her own, to adopt him (and they're implied to sometimes visit incognito). So kid gets a happy and healthy childhood, if nothing else. Usually, this kind of series makes the child either non-existent to begin with, short lived, or cut from the same cloth as their parents — refreshingly not the case here.
The manga also seems to be taking a different route with Paul: in the novel, the Evantale house is reduced to a small county, which Paul becomes determined to reform and revive properly, travelling to the neighbouring country (Latrice's homeland) to study, only staying with Agnes and Nazelbert on holidays (so our couple don't get disturbed in their newly-wed stage). He also falls head-over heels for Kelly which proves unfortunate: despite years of his obvious attempts to woo her, she doesn't even register that he likes her. Same thing happens to Connie. Girl's quite the heartbreaker. The distant epilogue is deliberately silent about what happens with that situation.