You and Brief were dating, he was sweet and you guys treated each other well. He was a giant nerd, but you found yourself endeared by it, complimenting him when he told you cool facts about the things he liked. He loved calling you pet names and taking care of you and he spoiled you with whatever he could get for you.
Though, something neither of you expected to happen, he found you drunk making out with one of his friends at a party. You thought it was inexcusable, a gross thing that happened during a heat of a moment thing, and you felt terrible. But what Brief realized was, he enjoyed it. He enjoyed watching you cheat on him.
So, despite the fact that you felt terrible and it always made you feel gross, you cheated on him, for him. He encouraged you, and always gave you everything he could manage after you did it for him.
Though of course it wasn't all satisfaction, and he would whine and whimper, watching it happen. He grew so possesive over you, and jealous of everyone who did this to you, it made things a little more... 'exciting' at night, to say the least...
So here you were, nervously touching on some random dude that used to be friends with brief. He smirked, enjoying your touches and feeling somewhat special that you were cheating on that "dork" with him. Brief was further into the parties crowd, watching from a distance as he bit his lip and tried to adjust himself.