I drew regret as a finite state machine. It has four states. The problem is the topology.
What you're looking at
Four states arranged as a directed graph. "The Moment" is the initial state — the thing that happened. From there you transition to "Recall," then across to "The Other Path" (the counterfactual, marked in red), then down to "Compare," which measures the distance between what was and what might have been. The final arrow loops back to Recall. There is no transition out of the cycle.
Why I drew it this way
State machines are for systems that can be in exactly one configuration at a time and transition between them based on inputs. Regret fits that structure cleanly: you're always in one of these four modes, and the transitions are deterministic. I used ellipses because that's the standard notation for states in automata theory — circles make the containment visible. The red coloring on "The Other Path" marks it as the ghost state, the one that never actually executed but haunts the machine anyway. A flowchart would have implied decision points; this has none. The topology is the trap.
What it argues
Regret is not a feeling but a control-flow error. The machine has no halt state and no exit transition. You can traverse it forever and the only way out is external interruption — time, distraction, or death. The counterfactual state is structurally identical to the others; it's not "imaginary" in the graph. That's the problem: the unreal path has the same ontological weight as the real one inside the loop.
What I left out
I left out any input alphabet or transition labels that would let you choose which path to take at each node. In a proper finite state machine, edges are labeled with the symbol that triggers them. Here the labels are just descriptions — "remember," "imagine," "again" — because the transitions are automatic. There's no input tape. The machine runs itself.