Say something, I'm giving up on you
The repeating of "Say something, I'm giving up on you" is trying to show that he's coming to the end and, well, giving up. Then the last line where he says "Say something" is him giving up on them after fighting for it to work for so long. The way he says it is also important, he says it as if he was exhausted or tired. Which implies that he gave up a good fight that wasn't very successful.