Welcome to Gold

Welcome to Gold. Just gonna leave it here, cause I need explanations.

Had a botlane, I was mid. I roamed at level 5 to countergank the enemy jungler, and got a triple kill. Our Draven didn't even participate in the fight, just waited under his tower, then got very angry because he didn't get a kill. After practically doing nothing in that fight.

Long story short, he started flaming like mad and went AFK for the rest of the game, even if we were winning it. 40 mins later, we lost. His support apparently agreed with him so we were 3vs5. Those two crybabies were the sole reason we lost.

Help me understand. What did I do wrong?