I don't think the mysterious object in question is important - it signifies the ways that in the wake of a breakup, the other party now has all this power over you, knowing your most vulnerable places and the things you really care about, and if they wish they can really start to unmake you by pressing on those tender spots. The second verse could be about the emotions surrounding the relationship: "It was mine now, something secret / something precious and rare / then it changed me, and I liked it / now I wish it wasn't there."
I don't think the mysterious object in question is important - it signifies the ways that in the wake of a breakup, the other party now has all this power over you, knowing your most vulnerable places and the things you really care about, and if they wish they can really start to unmake you by pressing on those tender spots. The second verse could be about the emotions surrounding the relationship: "It was mine now, something secret / something precious and rare / then it changed me, and I liked it / now I wish it wasn't there."