Theodore should know better than to take the cigarette from his lips, previously keeping him quiet as he should have been, to let his explosive nature take control of his mouth, and let his stupidity lead conversation for an answer that he, truthfully, didn't really mean.
As expected, he'd be left alone with his anger that soon became frustration with himself, instantly aware that he messed up— not only had this argument ended up terribly wrong, but also he had to shoulder the weight of guilt, from having made his girlfriend cry. How perfect, he sarcastically thinks to himself, Well done, Nott.
Making a girl cry makes his heart clench and his stomach twist into a knot. Theodore wonders what his mother would think, to see him berate his partner like his father did more than once; such a thing makes Theo consume another cigarette, and as the stick burns out, he goes on a quest to find forgiveness to meet him sooner than usual, which means, later.
Not many hours go by, because Theodore feels the urge to be on her arms again, and doesn't want her sadness to give place to anger instead. Knocking on her door, the dorm room he spent nights and afternoons on study dates, Theodore patiently waits— as patiently as his foot constantly clicking on the floor out of nervousness— outside, arms full of sweet briberies for his dolcezza.
"Cucciola," he sighs, calling out to her. The Italian Slytherin already feels his arms tired, from carrying a new plushie, a box of her favorite candy from Honeyduke's, and a small bouquet of her favorite flowers: "Can we talk? Hm? Forgive me just this once, cara mia."