SUBREDDIT: r/relationships
TITLE: Me [20F] with my friend [27 M] of a few months, I don't understand our interactions.
POST: I have a friend I sit next to 3 times a week in grad school. He's a nice, funny guy. I might have a little bit of a crush on him, but I figured that the romantic attraction is not returned, so I'm satisfied with being friends. However, he's acting funny and I thought someone might be able to shed some light on why.

We're friends on Facebook. We message a lot - sometimes about assignments, sometimes gossiping. We talked a little bit about his ex-girlfriend. He mentioned a bunch of girls in the class he was interested in. He calls me "dude" and "bro", so I figured that I'm like one of the guys and we're closer friends! We even talked a little about the kind of guys (me) and girls (him) that we're interested in, and I really thought we were developing more of a friend relationship. 

Recently he won't talk to me in person. He talks much easier to his guy friends and rarely looks me in the face. He's very silent and stoic in person, not making any jokes. I don't know what I'm doing wrong. Am I just a disappointment in real life compared to online?
TL;DR: 
I have a guy friend who I interact great with online, but he clams up in person. What's going on?