My friend seems to be mad at me, even though I didn't do anything to him?

[Courtney]

To give you some insight, we kind of have a history. We used to talk all the time and he admitted he liked me, but I turned him down because I was seeing this other boy (who I'm still dating).
I thought we were passed that and could be friends still, but he a couple months ago he told me he hates losing and feels like he lost. But we were still on good terms.
But this week hes been going through something I guess because hes been absolutely irritable and won't even look at me. He bitched me out on twitter for making a joke, and completely ignores me at school.
What should I do? I'm sad that hes acting this way, because hes a good friend and I do care about him.

[Kayla]

Private message him. And tell him not to be mad (not bossy like but politely) and let him know that even if he doesn't want to talk about what's up that your definitely always there to listen and give him advice.