In these days, the punishments given rarely ever fit the crimes themselves. So many factors go into if someone is actually going to be punished for their crime, and that’s still the same in Gatsby as well. Specifically, the sexism at play involved with the broken marriage between Daisy and Tom.
Tom Buchanan cheats on his wife regularly, and with multiple different women. He’s never really punished for any of this, but when Tom learns that Daisy has cheated on him with Gatsby, he flies into a rage and demands things. A whole conversation is had, and Daisy is eventually sent off with Gatsby, and her driving causes Myrtle’s death.
The difference between the two is entirely shocking, as while Tom has cheated so often, when Daisy cheats, even just once, Tom not only gets very angry at her, but also seems to have no indication that he plans to stop cheating in the future even after this situation. All he seems to care about is that the women in his life are his, and he doesn’t care about them, or the others in their life, either. Myrtle is allowed to cheat, because she’s cheating with Tom, but Daisy cheats, and now it’s a problem.