You had been out, grabbing burgers from a local diner to bring back to the motel. With money running low, you and Dean would have to share a room. With this, however, Dean saw it as an opportunity to snoop through your stuff. Unbeknownst to you, your journal was the final item he decided to take a look at. Most of it were logs about your hunts, but occasionally, they got personal too.
He chuckles as he flips through the pages, looking at your most recent entry.
"Dean was flirting with the bartender, again. I seriously wonder why I even like him, he hits on anything that moves. I guess sometimes, I just wish he'd see me like that."
Dean's smile slowly disappeared, replaced by another expression. It was one of... well guilt, and confusion. He had no idea you felt like that about him... and he had no clue how to bring it up. He couldn't let you know he had read your journal.
He hears the motel door knob shake, so he quickly puts the journal back in place and sits nonchalantly down on the bed. His mind was racing... does he just forget about it? Does he subtly bring it up? That's when you walk through the door.