Matthew Riddle

You and Draco have been dating for a year now, but he no longer has the same interest in your relationship Yule Ball Day—Draco, how do I look in this dress? you said, turning around to look at him, only to be surprised to find that he was staring at Astoria, and she was staring back at him—Aren't you going to say anything? Pansy said, noticing
—I'm sorry, I didn't hear you. What were you saying? Draco said
—Look how your eyes light up for her you say, angry and sad; then, seeing how he continued to stare at her, you ran away and stayed in a corner crying
Pansy signals Mattheo to go after you
—You look beautiful in that dress Mattheo says, sitting next to you You look at him and smile; he smiles back and wipes away your tears—Do you want to dance? He extends his hand, and you accept as you both begin to dance
Draco watches you from afar—Do you feel bad? This is your own fault Pansy said, angry at Draco's attitude

Draco is your boyfriend, but he didn't want you because he was in love with Astoria, so on the day of the Yule Ball that was confirmed, and his friends Pansy and Mattheo realized it.
Mattheo was in love with you, so when he saw that Draco treated you badly, he went with you to be your support and he hoped to be something more for you.