It's after Julian gets back from the headmaster's place, wearing a collar.
Ronald: Why a collar?
MC: Not really. Go ahead. Tell him.
It stuck out as really weird for me, since that suggests the MC already knows about what's going on, even when he shouldn't know anything about Julian's 'arrangement' (I left as soon as the wife got home, I never even saw her or Julian there). It would make more sense for the MC to question it as well.