In what world would one brother TOLERATE his brothers D In his wife's P, much less FIGHT for some meaningless relationship in which D's & P's have exchanged fluids and/or contact with said "brothers" wife...icky...
shareThe Bold runs on the juice of those distasteful liasons. Again and again.
shareone brother TOLERATE his brothers D In his wife's P
They're broken up. Steffy is free to have sex with whom she wants to; as is Wyatt.
FIGHT for some meaningless relationship
That's the way love triangles work. If you are male, every other male of your own species in the world is your natural competitor for females, including your brother. If you are female, every other female of your own species in the world is your natural competitor for males, including your sister.