Draco had a bad day, His score from potions were low, he lost in quidditch, and got scolded and compared by his father

And of course he took it out on you

"My father is right! He is FUCKING right that i don't deserve a fat wh0re like you! I can't even believe that I had put up with all your shit! I wasted 4 years of my fucking life!" He angrily yells, while you were sitting on his bed