[a] I'm not so sure about that... If the mantle boosts impulses that are already there, why wouldn't it boost the loving impulse just as strongly as the dark violent one?
Because it's a
Winter Mantle. It amplifies Harry's aggression, his territoriality, his sex-drive, his taste for violence.
It quiets his urge to compromise, his caution, and most if not all of his gentler emotions; it cannot mute them, but it often takes Harry an act of will to calm himself, to reconnect with those.
... also I doubt that Mab, even the mantle can force Harry to have sex, it's more complicated than that.
I think Winter Law takes no account of love. That doesn't mean the love doesn't exist, doesn't have impact; but love is a mystery to Winter, and the Law does not take it into account. Sex, in the Winter Court, is I think mostly about power; not affection or pleasure.
I'm pretty sure Winter Law would thus consider "go f--k someone" a perfectly valid command from the Queen of Winter.
And the WK Mantle would respond accordingly.
As you note, none of this actually
forces Harry to have sex ... But I think he loses the protections of the Mantle if he violates Winter Law so egregiously as disobeying a direct & legla order from the Queen; remember his proclamation "Fuck Winter Law!" in Molly's apartment.