It's not as simple as 50/50 though. Take three couples, they all have assets of 250K to split 50/50.
Person A lives in London, kids stay in local primary school which they are thriving at, and they must re-house themselves on 125K. Their partner swans off to Thailand (their choice), where rents/properties are considerably cheaper. They are having the time of their life with no responsibility? Fair?
Person B lives in the North. They can rehouse themselves (mortgage free) for 125K. Their partner remains and brings up the children 50/50, doing their fair share of parenting, structures their work around the children's needs equally. Pays half of school trips/clothing etc. They both earn the same amount near enough. Fair?
Person C lives in middle England discovers their partner squandered £1m on prostitutes, gambling and reckless living, and they have 250K in the marital pot when this is discovered. Fair?
Person D married 30 years. Person E married 1 year. Person F has six children....
That's why fairness is so very subjective and 50/50 is only fair in the most unusual circumstances.