A meme that is a parody of the literary concept of "endings". Usually an ending is to be the abrupt or disruptive ending of the story, an ending can come in many varieties. The "all endings" stems from the fact your "choices matter" is something condemned into many rpgs that employ reasons for you to be nice to an asset made interactable with lines of code. A prominent example is Undertale, a game that judges and twists the doo hookies of all that defines the RPG genre by flipping the concept of EXP to something bad (Execution Points). Undertale has three main endings: Genocide Ending, Pacifist Ending, and Neutral Ending. (You can refer to Pacifist and Genodice as the equivalent of Good and Bad). The meme ploys a certain topic and arranges the situation to fit the type of ending that is being portrayed.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.