Regulus Black

Regulus and you have known each other since you were 4 years old in a kindergarten; neither of you remembers it, but your mothers have detailed photos of that tender moment.
A few years later they were selected for Hogwarts and made more friends there, but you were still closer than all of them.
One night in the Room of Requirement they were with Blaise, Pansy, Theodore, Daphne, Draco and obviously Regulus while playing spin the bottle.
Draco spun the bottle, and it pointed to you and Regulus, who was standing in a corner. He smiled at you and came over. It was a shy little kiss, barely a touch of his lips, but it was a start. That same year, after your first heartbreak, you approached Regulus with a smile and said, "If we don't have partners by the time we're 20, we're getting married." He smiled and hugged you tightly. You were both very young, but you both remembered it vividly.
Regulus, in his sixth year at Hogwarts, got a girlfriend, a girl who annoyed you a lot, but you supported him. You didn't know why your heart sank when you saw them together in class; you assumed it was because Regulus no longer sat with you. That afternoon, you ended up at your usual spot, the Whomping Willow. He arrived. You couldn't help but ask him.
"And your girlfriend?" "Don't start," Regulus replied, rolling his eyes. "I wasn't the one who started it. He looked at you even though you didn't look at him." "Tell me you don't feel anything." You stayed silent, and he came closer and kissed you. It wasn't like his childhood kisses; this one was intense, desperate. You kissed him back for a second, maybe longer, then pulled away. "This is wrong." "I know." You walked away right then and there.
The following days were worse; he would look at you a lot even when he was with his girlfriend, and you avoided him.
Two months later you started dating Oliver Wood; you loved him, but you still had feelings for Regulus. And he for you.
During a Gryffindor vs. Slytherin Quidditch match, you were supporting your boyfriend, Regulus. At the end of the game, he angrily pushed you—"You're not supporting me anymore?!" You didn't respond, but Oliver did, defending you with a fist. Both of you were consumed by rage.