I think it's about bittersweet memories of a broken relationship ("wheels won't turn when the other has gone"), and that even though you might have moved on and don't want reminders ("things that nobody wants any more") you still cherish the memory of the time you were in love. "All those playing cards pinned to the spokes" sound like affairs or deceptions that built up over the years, and somehow there was a tipping point ("seasons can turn on a dime").
I think it's about bittersweet memories of a broken relationship ("wheels won't turn when the other has gone"), and that even though you might have moved on and don't want reminders ("things that nobody wants any more") you still cherish the memory of the time you were in love. "All those playing cards pinned to the spokes" sound like affairs or deceptions that built up over the years, and somehow there was a tipping point ("seasons can turn on a dime").