An event which is made sadder by a later event. Differs from Harsher in Hindsight in that the events may not necessarily be bad or harsh. The events that are Heartbreaking in Hindsight might be a Heartwarming Moment and it is only until the later event that you see sadder subtext in the first one. Compare Harsher in Hindsight, Heartwarming in Hindsight, Tear Jerker. Contrast Hilarious in Hindsight.