Complex sentence: During his time with the Americans, he had an on-ice fistfight with Portland Winter Hawks goaltender Byron Dafoe, with whom he later had a friendly rivalry in the NHL, each serving as the other's best man in their respective weddings.
Split into simpler sentences: During his time with the Americans, he had an on-ice fistfight with Portland Winter Hawks goaltender Byron Dafoe. The two later became friendly rivals in the NHL, each serving as the other's best man for their respective weddings.