Touch her and die names a type of romance hero who will defend the woman he loves with everything he has, and means it literally. The appeal lies in the direction of that ferocity: it never turns on her, only outward, on her behalf.
The phrase is reader shorthand for a scene: a man who is otherwise controlled to the bone loses that control the instant someone gets too close to her. She is never the object of the violence. She is its reason.
The signs are physical. He puts himself between her and the room, usually without a word. He knows every exit. And he has a past that made him dangerous: military, family, business.
Aleks in “Ma'am” moves into your guest room, checks your audience through a camera lens and listens to every concert from the side aisle. Dante in “Under His Protection” turns the threat into policy: he is the new capo, and his protection comes with terms. Whether you accept them is your move.
At Everglow you do not just read it. You are the protagonist, and every chapter ends with your move.