QuadRom flags because I couldn't find any simple ones I liked as much. Feel free to use and edit (I made them with intent to combine flags), credit appreciated but not required!
My personal explanations / how I define each quadrant under the cut!
Matespritship: AKA Flushed romance or RedRom, concupiscent love quadrant between two (or more) people. Denoted with a heart symbol, lovers are called matesprits. Commonly equated to human romance.
Kismesissitude: AKA Pitch romance or BlackRom, concupiscent hate quadrant between two (or more) people. Denoted with a spade symbol, haters are called kismesises. Commonly equated to romantic rivals and involves pushing the other towards betterment.
Moiraillegiance: AKA Pale romance, (typically) platonic love quadrant between two (or more) people. Denoted with a diamond symbol, lovers are called moirails. Commonly equated to queer-platonic relationships, involves calming and protecting the other emotionally.
Auspistism: AKA Ashen romance, platonic hate quadrant between 3 (or more) people. Denoted with the clubs symbol, the primary member of the group is called an auspistice while the others are auspistees. Ashen romance is felt by a third party to step in between harmful rivals and mediate conflict. The third party is often (but not always) a moirail of one of the auspistees.