Kismesic is a microlabel of quadrantromantic ― part of the Quadrant System ― and denotes attraction in the pitch/caliginous quadrant.
The term for caliginous feelings is hate, though it's most similar to frustration. A pitch crush would be someone you're intensely frustrated by, but admire on some level nonetheless. It's a powerful drive to one-up them and have them best you in turn. You might want to bring harm to your kismesis, but you do not want to kill or break them. The impotence of knowing this person could be perfect for you but isn’t because of some little thing they insist on doing is a powerful feeling.[1][2][3]
A pitch partner is called a Kismesis, and a pitch relationship is called a Kismesissitude. A kismesissitude is symbolised by <3< (in text) and the ♠️ symbol.