I'm sure you're sick of.
Third parties are pointless in America because no third party can make a real political difference.
No third party can make a real political difference because ours is not a parliamentary system. The problem is not merely that our system lacks proportional representation. The Canadian system lacks proportional representation, yet the NDP and the Bloq Quebecois play important roles. The fact is that if ours were a parliamentary system even one without proportional representation we might well have a Democratic-Green coalition government right now. Since our actual system doesn't allow government by coalition, however, the only way for Greens or any other third party to make a political difference is to form a coalition with one of the two major parties presumably, in your case, the Democrats before the election.