i dont get the end???

Two tops marked the bottom at the same time so the three of them become pairs (with 3 people). The black-haired top marked him because he likes the bottom and because he was provoked by the blond top (I assumed he's blond). And the blond likes the black-haired top but they can't pair since they're both alphas, so he marked the bottom too so now he can be paired with the black-haired indirectly