Cubemate
During the Coin Incident's highest-energy phase, many of Dwaia's cubies popped out and underwent fission, splitting off into pairs of entities. Two such entities are always very complimentary to each other, and as such are called each other's cubemates. For example, one cubie fissioned into a hat and a hatrack, both sentient and madly in love with each other. Cubemated entities can range from inanimate objects and structures, to plants and animals, and even to people.
Unfortunately, when cubemates get too close to each other, they irreversibly fuse back into a cubie, destroying all traces of consciousness. Additionally, it is hard to know whether you yourself are a cubemate or not. This is because sentient cubemates often formed with fully detailed memories of fake lives, and often spend decades or centuries in a coma before waking up. Thus it is always worth wondering whether that person you really like is your soulmate, or whether you are cubemates.
Treatment
The only known treatment for cubemateship is CBT (Cube Bending Therapy).