Complex sentence: However he refused to marry Gigi because she, though a nice woman when with him, was in reality quite a sore loser who threw tempertantrums while on the verge of losing mahjong games, who could not understand that he couldn't stand the way she behaved.
Split into simpler sentences: However he refused to marry Gigi because she, though a nice woman when with him, was in reality quite a sore loser who threw temper tantrums while on the verge of losing mahjong games. She could not understand that he couldn't stand the way she behaved.