Heartbreaking in Hindsight

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 Funny Aneurysm Moment (funny that turns disturbing or sad), Harsher in Hindsight, Heartwarming in Hindsight, Tear Jerker. Contrast Hilarious in Hindsight.

Film

 * In the film Black Panther M'Baku gives a giant smile of relief when T'Challa's family successfully revives him after his Near-Death Experience, showing that he does have a soft side. In Avengers: Infinity War, T'Challa gets dusted by Thanos, along with a good number of the Wakandan forces. All M'Baku can do is stare at the battlefield with an anguished expression.
 * Sticking with the Marvel Cinematic Universe, Tony Stark's words to Peter Parker in Spider-Man: Homecoming of "And if you died, I feel like that's on me. I don't need that on my conscience." become that much more painful in Infinity War when Tony is helpless to prevent Peter's death from the Snap.

Western Animation

 * The show Tuca & Bertie has quite a few:
 * In a heartwarming moment between Speckle and Bertie, where Speckle creates a romantic roleplay for Bertie after she admits, following an episode of miscommunication, she wants to add some surprises to their sex routine. They end up reviving the spark between their relationship. In the season one finale, Speckle calls out Bertie for refusing to answer her calls for a week, and was worried that something had happened to her. He says that he can't be the rock in their relationship to constantly provide emotional support or automatically knowing her needs. They do make up, but Bertie admits that she has a lot of work to make up for ghosting Speckle, to be his rock.
 * When a sloshed Speckle witnesses Tuca taking emotional abuse from her aunt, he whispers for her to stand up to the lady. Later, he comforts Tuca that You Did the Right Thing by tearing up the woman's check after her aunt belittles her single mother. In the season finale, Tuca finds out that her aunt is in the hospital from cirrhosis, and their last conversation was a huge fight.