Sorry, im going to answer loads of you're comments in one.
First of all, its not about the %, its about both being reasonably both partys being reasonably housed.
She wants a 4 bedroom house, and with 3 children, for most of the week, I completely agree.
I haven't asked for the same, I've asked for a 3 bedroom house, to house the children appropriately when with me, as the 2 boys can share, as they will spend less time with me.
As for my argument, there is enough in the pot + both our mortgage raising capacity to house us all to the above mentioned needs.
Our current family home is worth 500k its a nice detached, spacious house. She could get a nice 4 bedroom house for 400k in our area, which would be totally adequate.
And this would allow me to buy a 280-300k adequate 3 bedroom home aswell.
If her parents want to dip in to there pockets to help there daughter, thats between them.
She works 8-3 4 days a week, some days a bit earlier and a bit later, which is do the majority of the pick ups.
As for me be grudging her having a day off during the week, currently I begrudge it as when I get home im the one who has to clean up the kids breakfast stuff left all over the table and the house is a mess, when shes been off socialising (I start work at 6am).
Our dynamic is i do the cooking etc, which isn't a problem, it works for both of us.
I have no problem with her having a social life, we all need friends. But because she chooses to do that and then franticly meet them at the weekends, goes away etc. Its always been at the detriment of family time, as she plays catch up at the weekends with work and can never do somthing as a family. Its been a bug bear of mine for years, but we all see the world differently I guess.
Ultimately the friendliness fades over time.