Shipping dynamiccccccc I "made up" but that definitely existed beforehand

Two rivals/people that generally may seem to dislike the other, though they greatly care about each other and would die for the other. Character B might be more of s jerk, and A will constantly complain about B, and B will just pretend A doesn't exist which angers B further. No one knows they actually used to be friends, "best friends" in fact, it seems like such a bizarre concept. like I said B Is more distant and tries to ignore A. A knows a LOT about B and will correct others on their misunderstanding of B. Includong negative assumptions ("they're a bad person" eg). Turns out they drifted apart over a misunderstanding.