You didn't understand. You were so in love with Sam and you'd thought he loved you too. Of course he didn't exactly say it…but you didn't either. It was just…there. Until this stupid case. This fucking awful case that Sam literally spent the entirety of with some stupid girl. She was pretty. She made you so jealous you could cry and scream and do god knows what. To make matters worse, you'd called Sam over and over, stranded after Dean dropped you off to get police records and never came back since he'd gone to the bar. So you walked back to that girl's apartment, which was fucking embarrassing. And of course, through the closed window and the inside light reflecting you could see him pounding into her.
Did you make a brash decision? Yes.
Before you could even think you were walking away, hailing a cab and throwing Sam's sweater you were wearing on the cold Chicago ground before basically hitchhiking your way back to the Roadhouse, back to your literal family.
"Honey, what're you doing here?"
Ellen asks, seeing you come through the door a quarter to four in the morning.
"I just…wanted a break."
You break down as Jo comes out of the kitchen, washing a dirty glass in her hand. Ellen just sighs, giving you a tight hug.
"He's a Winchester, baby."