While I'm all for accepting things as they are, the problem isn't what conservatives and liberals need to do next - it's getting back to a foundational understanding of where ethics and rights derive from. Our founders knew this, while today man seeks to be the arbiter of truth. There is no further argument to be had.
As for the SCOTUS defining marriage, legislating from the bench as it so often happens - Dietrich Bonhoeffer said it best: "Marriage is performed not by government, but in the presence of Government." Government didn't create marriage nor can they redefine it whatever happens.