David: he'd try not to show, but deep down, he's sad. He barely talks to anyone, and when someone tries to talk to David, he'll snark at them, telling them to leave him alone.
Then, he'll drown his pain in a pity kill.
Paul: he smokes his entire secret stash. He was saving it for special occasions, but this was a necessity. Then, he'll go through your favorite songs and think of you while holding onto a leather jacket you left behind. It smells like you...
Dwayne: he'll visit the boardwalk every night, hoping to see you. He waits on his bike for hours. His plan was to try and talk it out with you, to see if the two of you could work it out. But no so luck occurs...
Then, he'll drive home and go into his room, sitting on a chair and crying a little.
Marko: he will beg you to stay. Literally. He'll go to where you work and plead you to talk to him, that the two of you could overcome anything. But it doesn't work.
So after five attempts, he goes home and crawls into bed, the blanket pulled up to his nose.
He thinks of all the fun times you've had just to torture his heart.