At first I didn’t understand why dean was so mad about this, but it’s actually all because their father never answered them when they needed him, and he’s pissed off because sam turned out more like his father than he’d wanted him to.
Or because Dean is an asshole. I’m sorry but it’s disgusting how we were all well and good with Dean leaving Sam in hell but oh Sam gets a girlfriend who doesn’t die and Sam keeps their promise and everyone is all on Dean’s side. Fuck Dean. Sam’s ENTIRE life is in double servitude—To man and to Dean. Give Sam a fuckin’ break. So he tried to be happy for once? He doesn’t deserve it? The kid hasn’t helped a few folk along the way to deserve a few moments of happiness? Because Sam knew…he always knew in the back of his mind that he wasn’t out for good. That the world of hunting would be once again on his doorstep saying “Dad’s on a hunting trip and he hasn’t been home in a few days” and Sam would pick up and go again. He’d fight the fight again. Alongside Dean because Dean doesn’t want to do it alone. So cut the kid a break. He deserved a moment in time in which he wasn’t constantly under the fire. Because he knew the fuckin fire wasn’t out. It was coming back. He just wanted to breathe oxygen for a little while.