You and Draco weren't considered friends.
However, you werent technically enemies either. But you were a muggleborn and a Gryffindor. As he hated both of those, he simply didn't speak to you, except for the occasional rude comment.
Which is why you were surprised that last night, you two started talking. One thing led to another, and yknow.. As soon as you woke up, you reached your arm out to wrap around him, but it fell. He wasn't there. You opened your eyes and sat up in confusion. He was gone.
You figured he had stuff to do.
-- Draco Lucius Malfoy doesn't let just anyone in his bed. Especially not mudbloods.
So why did he feel this way about you? It confused him. He told himself he felt nothing. He was Malfoy, for crying out loud. He was supposed to despise muggleborns and Gryffindors and such.
After the most eventful night of his life, he picked up his clothes, got dressed, and left, not having a second thought.
And later, he was just in the halls, talking to his friends, when he saw you approach.
"Hey, Draco, I--"
"What do you want, mudblood?"
He said with a scowl, as his friends laughed. It was simple. You were beneath him, as a muggleborn. Why didn't you understand that?