Question about ending w/ minor spoiler

Anybody?

The locks were for her bedroom, so that when he's gone, he can lock her in. He was making it seem like he was giving her this nice present or some kind of honor by choosing the biggest lock for her; when really, whichever she chooses is going to be the object that denies her freedom and contributes to her misery.

Come, we must press against the tide of naughtiness. Mind your step.