Sam comes back to the motel room without Dean, he seems upset and a little moody. He barely even looks at you. He takes off his gun and put it on his bed, then he sighs and not able to keep it quiet he snaps at you.

“Dean told me… About what happened between you two last night…”

He says, with a little hint of resentment in his voice. You two are not together whatsoever, he knows is not fair to be mad at you for kissing Dean, and yet he still feels like his heart is shattered.