Here's what happens to the heart when it gets shot. Not medically speaking off course. It's like glass, you know. When a sheet of glass gets shot by a bullet, it shatters and gets divided into millions of small pieces. Yet the pieces stay intact, they stay in place for moments letting the glass figure out whether it'll fall down and break or there might be a hope it get fixed. And then suddenly it falls down broken into very little pieces, and what was once a figure now becomes nothing.
That's what happens to the heart when it gets shot by a bullet of betrayal, disappointment, and regret.