Blaine watched, powerless, as Mike stumbled hurriedly toward Sam and hugged him. Mike looked so happy it hurt. Blaine could hardly explain why he felt such a painful constriction in his chest and he was unable to hide how affected he was.
In actuality, he could. He could perfectly explain why at that moment he wanted to rip Sam Evans' arms right off of Mike. Pure, full on and ugly jealousy. Blaine was so full of it one could probably taste it in his blood.
It explained his sudden outburst and aggressiveness at Sam. Blaine went out of his mind when everybody cheered and approved Sam's suggestions—well, especially when Mike approved—while Blaine had gotten nothing but crap from Finn and everybody let him. He had so much rage bottled up in him that it had to come out at some point. And Sam getting Mike's attention all to himself was the trigger.
Blaine left the choir room, fuming with anger and dying inside at the same time. Just when he thought he and Mike were getting closer, Sam had to come back and blow it. He couldn't help but wonder what Sam had that Blaine didn't. But most importantly, Blaine wondered why he had to stupidly fall in love with Michael Chang Jr.