Splitting relationship property as the primary financial contributor

My mother is just starting down the road of splitting money/property with her de facto partner of 7 years.
She was always the bread winner, paid for majority of things. He didn’t earn as much and was just terrible with his money. Law says he’s entitled to half of everything.

My question is, all the money she’s made during their relationship and has spent on him. Is that not already his share or some of it spent?

His lawyer want the past 7 years of financial history from my mother. Are they looking to see how much she has made over that time? What’s going to happen?