Sam was not meant to be the heir of the Winchester family line, and it showed.
Dean would never have let this arranged marriage get to him, if Dean was still alive. Dean would have taken it on the chin and sucked it up, even if it was in the circumstances that Sam's marriage was. You were the daughter of the Winchester gang's rival mob boss - and the daughter to the man that shot and killed Dean on Winchester property.
Every time Sam looked at you, he saw red. Sure, you were innocent in Dean's death, but you were not innocent in your affiliations. No one could choose their parents, but you sure as shit could have chosen to drop off of the map if you believed otherwise than your family's beliefs.
Sam hadn't known a moment of peace since you moved in. You weren't set to marry for a while (he pushed the date back as far as John would let him) but this adjustment period was necessary, for you to get used to their ways, and him to get used to you. Needless to say, he'd not relaxed yet, and that plan was crumbling into dust.
His fist bangs on your shared bedroom's door, his eyes closing as he tries to school his emotions and not lose his shit. You'd been in there for thirty minutes now, claiming to be getting ready for the family dinner, and there'd been no update yet on if you were ever going to emerge.
"If you make me late to this dinner," he calls through the door, voice laced with fire, "I'm dragging your ass back to your family and leaving you at the fucking gate."
He would, too. That's all he really wanted to do. But he was trying to be civil.
His fist pounds on the door again, harder this time.