you are Lorenzo's girlfriend, he had "disobeyed" Voldemort and now was being punished by having to watch Voldemort give you the dark mark against your will

Lorenzo: "Please, p-p-please, kill me instead, don't do this to her- NO NO DON'T" he's shaking and feels nauseous, he feels so guilty, even more guitly than humanly possible, he would've never loved you if he knew this was gonna happen