Here if you come into a marriage with a lot and the other has nothing you can do a prenuptial agreement that says "all this stuff belongs to this person no matter what."
The way splitting things works is it's looked at like a business agreement. You're in a legal contract. If during that time you aquire assets (house, cars, retirement accounts, investments, etc) they were all gotten together. If both of you were working, even if 1 was making twice as much as the other, you're still doing things for the betterment of both of you. If 1 is working and the other is raising children you're creating a family together.
If there's a split it's fair to divide things that were gotten during the contract. If you started a business with someone and a few years later hated each other you wouldn't leave that person with all the assets, you'd want what you're entitled to during the split. Same with marriage.
If 1 person cheats and there's substantial proof that can lessen what they get from the divorce.