The true reason Pluto is an aro symbol is precisely because people tie the amount of love and care this wonderful celestial body receives to which label it has. Just because a relationship with someone is not labeled as romantic should not mean that this relationship has to be treated as less worthy of time and care and effort. Just because Pluto is not labeled as a planet does not mean it is less worthy of our time and care and effort. Now, Pluto and it's moon Charon are tidally locked, meaning they always face each other with the same hemisphere. Pluto's heart is always facing away from Charon. Some articles have phrased this as being tragically romantic, but I disagree! Here are two celestial objects orbiting each other for billions of years, and they are doing this while Pluto keeps it's heart hidden. Because in this case, love is not part of the equation that makes up their bond, romance does not play a part in their gravitational pull towards each other. That's aro as fuck, in my humble opinion.