de bene esse: literally, of well-being, morally acceptable but subject to future validation or exception
Though it's ubiquitously used today (at least among the emoji-reliant set), the heart hasn't always been a stand-in for romantic feelings. A quick Wikipedia scour confirms its use was popularized in 16th century, but no one’s entirely sure why. A Slate explainer from 2007 offers a few theories: the heart resembles the leaves of a plant once used as makeshift contraceptive pills; unskilled artists tried, and failed, to replicate the actual appearance of the human heart, which Aristotle said was the source of feeling. Gloria Steinem wrote her own theory in an introduction to The Vagina Monologues, explaining that the heart replicates the curves of a womanly figure, the source of erotic love.
Regardless of the reason for its rise in use, the heart symbol wasn’t around -- at least as a metaphor for love -- until the mid-13th century, when its first known use was recorded. In a small drawing adorning a decorative letter preluding a block of text in Roman de la poire, a suitor kneels before a crowned lover, granting a heart-shaped offering. The text is a medieval French work about falling in love. "Poire" means "pear," and the figure in the image resembles both a heart and a pear. As in the story, the image uses a pear, pictorially similar to a modern-day heart symbol, as a metaphor for romantic love.
Before that, the sloped-and-pointed symbol was used to decorate manuscripts, but it typically represented a leaf, not the profound and enigmatic feeling of romantic love. So when it comes to the Twitter change, if your heart’s not in it, remember that historically speaking, the symbol is interpretable.