On the basis that if you divorce money goes 50:50 generally
No, it doesn't, especially if you have children.
For example, db, happy marriage, joint accounts, 3 young kids, savings, isa, relatively low mortgage, nice, new family car.
Unbeknown to him his wife is sleeping with her colleague. One weekend she asks him to stay our parents because she "needed some space". Changed the locks, and he has never been allowed back in the house, as OM moved in.
By the time he realises, all the joint accounts and savings accounts are empty, and she's taken out an overdraft. Stuff for home improvements and the kids, apparently.
Court accepted this, so no money to split. Overdraft is taken off the house value. Roughly £150k equity in the house, he gets £15k and he had to take her back to court twice to get it as that's all she can increase the mortgage to in her sole name. She has to buy him out as another man is living there, and can't be made to sell as it's the kids home.
She keeps the car, needed for the kids, and everything in the house as he'd have had to go round with bailiffs as she wouldn't allow him in to collect anything.
So after solicitors fees are paid, db got pretty much nothing. Certainly no where near 50%.
It's a nice idea that everything will be split fairly, but it very rarely happens.