There was also just a lot of plain misinformation...
-Choosing to try to capture the shota barbarian without diplomacy will blow back on your face because it is the plain wrong choice, nothing to do with "strong female protagonist" or "weak female protagonist". If you make the wrong choice you get punished and the only way to regain their trust is agreeing to one of the nude meetings, but that's it. Anything you do after that is your own choice. If instead you make the correct choice of not antagonizing your local ally for no good reason (and you know you can trust him since the game shows you a cutscene before about how he genuinely wants to reach out to you for mutual help), you can progress the barbarian conquest without doing anything sexual with them. Doing sexual things like the naked rituals or whatever will make the game easier but it is not mandatory, I just don't think there is a conclusion to the barbarian war yet so you don't get anything for trying to just beat the barbarians to 100%.
-The entire story is that the Queen is in a precarious position, pretty much none of the kingdom's institutions support her, her family is in debt and her kingdom is weakened. She is in no position to go around making reckless decisions or going around humiliating her strongest subjects. Also the Duke doesn't publically humiliate her, it is not public knowledge that he wants sexual service from the Queen in exchange for his allegiance, he words his oath the way he does because he wants to make it clear to the Queen that if she still wants him as a "friendly" subject then his offer is still open, but he is also giving himself an out to undermine her without completely going back on his word (he could make some bullshit up about how the Queen didn't fulfill her part of their personal agreement without really revealing the sexual nature of it). I do hope that eventually we can get a more permanent solution over the Duke (finding a way to blackmail him, supporting a claim from a relative of his to usurp him, etc) but that's more of a lategame thing, I think him getting a heavy slap to the face and you getting to force him to help out the kingdom is good enough for the current state of the game.
Point being, you are free to play your Queen as a "strong female protagonist", you just can't go around conquering the whole world and instantly defeating all your enemies and anyone you don't like because this is not a power-fantasy game with superpowers and shit, also there's just not a lot of sexual payoff for it because it wouldn't make sense with the story.